Variable magnification optical system, optical apparatus, and method for producing variable magnification optical system

ABSTRACT

A variable magnification optical system comprising, in order from an object side, a first lens group and a plurality of lens groups; upon varying a magnification, a distance between the first lens group and the plurality of lens groups being varied, and distances between respective lens groups in the plurality of lens groups being varied; the plurality of lens groups comprising an object side focusing lens group which is moved upon carrying out focusing and at least one image side focusing lens group disposed in a more image side than the object side focusing lens group and moved with a trajectory differing from that of the object side focusing lens group, upon carrying out the focusing; and
         the predetermined conditional expressions being satisfied, whereby variations in aberrations upon varying magnification from the wide angle end state to the telephoto end state as well as variations in aberrations upon carrying out focusing from an infinite distance object to a close distance object can be suppressed superbly.

TECHNICAL FIELD

The present invention relates to a variable magnification optical system, an optical apparatus and a method for manufacturing the variable magnification optical system.

BACKGROUND ART

There has been proposed a variable magnification optical system that is suitable to be used for a photographic camera, an electronic still camera, a video camera or the like. For example, refer to Japanese Patent application Laid-Open Gazette No. 2004-198529. However, in the conventional variable magnification optical system a variable magnification optical system is not enough to suppress variations in various aberrations upon focusing.

PRIOR ART REFERENCE Patent Document

-   Patent Document 1: Japanese Patent application Laid-Open Gazette No.     2004-198529.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a variable magnification optical system comprising, in order from an object side, a first lens group and a plurality of lens groups;

upon varying a magnification, a distance between said first lens group and said plurality of lens groups being varied, and distances between respective lens groups in said plurality of lens groups being varied;

said plurality of lens groups comprising an object side focusing lens group which is moved upon carrying out focusing and at least one image side focusing lens group disposed in a more image side than the object side focusing lens group and moved with a trajectory differing from that of the object side focusing lens group, upon carrying out the focusing; and

the following conditional expressions being satisfied:

0.60<(−f1N)/|f1|<1.80

0.2<BFw/fw<2.0

where f1N denotes a focal length of a lens which has a strongest negative refractive power in lenses in said first lens group, f1 denotes a focal length of said first lens groups, BFw denotes a back focus of said variable magnification optical system in the wide angle end state, and fw denotes a focal length of said variable magnification optical system in the wide angle end state.

Further, according to a second aspect of the present invention, there is provided a method for manufacturing a variable magnification optical system comprising, in order from an object side, a first lens group and a plurality of lens groups; comprising the steps of:

constructing such that, upon varying a magnification, a distance between said first lens group and said plurality of lens groups being varied, and distances between respective lens groups in said plurality of lens groups being varied;

constructing such that said plurality of lens groups comprises an object side focusing lens group which is moved upon carrying out focusing and at least one image side focusing lens group disposed at a more image side than the object side focusing lens group and moved with a trajectory differing from that of the object side focusing lens group upon carrying out the focusing; and

constructing such that the following conditional expressions are satisfied:

0.60<(−f1N)/|f1|<1.80

0.2<BFw/fw<2.0

where f1N denotes a focal length of a lens which has a strongest negative refractive power in lenses in said first lens group, f1 denotes a focal length of said first lens groups, BFw denotes a back focus of said variable magnification optical system in the wide angle end state, and fw denotes a focal length of said variable magnification optical system in the wide angle end state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a variable magnification optical system according to a First Example.

FIG. 2A, FIG. 2B and FIG. 2C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the First Example.

FIG. 3A, FIG. 3B and FIG. 3C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the First Example.

FIG. 4 is a sectional view of a variable magnification optical system according to a Second Example.

FIG. 5A, FIG. 5B and FIG. 5C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Second Example.

FIG. 6A, FIG. 6B and FIG. 6C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Second Example.

FIG. 7 is a sectional view of a variable magnification optical system according to a Third Example.

FIG. 8A, FIG. 8B and FIG. 8C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Third Example.

FIG. 9A, FIG. 9B and FIG. 9C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Third Example.

FIG. 10 is a sectional view of a variable magnification optical system according to a Fourth Example.

FIG. 11A, FIG. 11B and FIG. 11C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Fourth Example.

FIGS. 12A, 12B and 12C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Fourth Example.

FIG. 13 is a sectional view of a variable magnification optical system according to a Fifth Example.

FIG. 14A, FIG. 14B and FIG. 14C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Fifth Example.

FIG. 15A, FIG. 15B and FIG. 15C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Fifth Example.

FIG. 16 is a sectional view of a variable magnification optical system according to a Sixth Example.

FIG. 17A, FIG. 17B and FIG. 17C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Sixth Example.

FIG. 18A, FIG. 18B and FIG. 18C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Sixth Example.

FIG. 19 is a sectional view of a variable magnification optical system according to a Seventh Example.

FIG. 20A, FIG. 20B and FIG. 20C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Seventh Example.

FIG. 21A, FIG. 21B and FIG. 21C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Seventh Example.

FIG. 22 is a sectional view of a variable magnification optical system according to an Eighth Example.

FIG. 23A, FIG. 23B and FIG. 23C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Eighth Example.

FIG. 24A, FIG. 24B and FIG. 24C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Eighth Example.

FIG. 25 is a sectional view of a variable magnification optical system according to a Ninth Example.

FIG. 26A, FIG. 26B and FIG. 26C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Ninth Example.

FIG. 27A, FIG. 27B and FIG. 27C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Ninth Example.

FIG. 28 is a sectional view of a variable magnification optical system according to a Tenth Example.

FIG. 29A, FIG. 29B and FIG. 29C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Tenth Example.

FIG. 30A, FIG. 30B and FIG. 30C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Tenth Example.

FIG. 31 is a sectional view of a variable magnification optical system according to an Eleventh Example.

FIG. 32A, FIG. 32B and FIG. 32C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Eleventh Example.

FIG. 33A, FIG. 33B and FIG. 33C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state, and in the telephoto end state, of the variable magnification optical system according to the Eleventh Example.

FIG. 34 is a view showing a configuration of a camera equipped with the variable magnification optical system.

FIG. 35 is a flowchart schematically showing a method for manufacturing the variable magnification optical system.

EMBODIMENT FOR CARRYING OUT THE INVENTION

Next, a variable magnification optical system according to the present embodiment, an optical apparatus and a method for producing the variable magnification optical system, will be explained.

The variable magnification optical system according to the present embodiment comprises, in order from an object side, a first lens group and a plurality of lens groups;

upon varying a magnification, a distance between said first lens group and said plurality of lens groups being varied, and distances between respective lens groups in said plurality of lens groups being varied;

said plurality of lens groups comprising an object side focusing lens group which is moved upon carrying out focusing and at least one image side focusing lens group disposed in a more image side than the object side focusing lens group and moved with a trajectory differing from that of the object side focusing lens group upon carrying out the focusing; and

the following conditional expressions (1) and (2) being satisfied:

0.60<(−f1N)/|f1|<1.80  (1)

0.2<BFw/fw<2.0  (2)

where f1N denotes a focal length of a lens which has a strongest negative refractive power in lenses in said first lens group, f1 denotes a focal length of said first lens groups, BFw denotes a back focus of said variable magnification optical system in the wide angle end state, and fw denotes a focal length of said variable magnification optical system in the wide angle end state.

Here, in the variable magnification optical system according to the present embodiment which comprises, in order from the object side, the first lens group and a plurality of lens groups; upon varying the magnification from a wide angle end state to a telephoto end state, a distance between said first lens group and said plurality of lens groups being varied, and distances between respective lens groups in said plurality of lens groups being varied, thereby it being possible to attain superb correction of aberrations upon varying the magnification. Further, in the variable magnification optical system according to the present embodiment, the plurality of lens groups comprises an object side focusing lens group which is moved upon carrying out focusing and at least one image side focusing lens group disposed in a more image side than the object side focusing lens group and moved with a trajectory differing from that of the object side focusing lens group upon carrying out the focusing, whereby it is possible to suppress effectively variations in spherical aberration and other various aberrations upon carrying out focusing from an infinite distance object to a close distance object.

Meanwhile, in the present embodiment, a lens group means a portion which comprises at least one lens separated by an air space.

The conditional expression (1) defines a ratio of a focal length of a lens which has a strongest negative refractive power in lenses in the first lens group, relative to a focal length of the first lens group. With satisfying the conditional expression (1), the variable magnification optical system according to the present embodiment can correct effectively coma aberration and other various aberrations, and can suppress variations in spherical aberration and other various aberrations upon varying the magnification from the wide angle end state to the telephoto end state.

When the value of (−f1N)/|f1| is equal to or exceeds the upper limit value of the conditional expression (1) of the variable magnification optical system of the present embodiment, refractive power of the first lens group becomes strong, and it becomes difficult to suppress variations in spherical aberration and other various aberrations upon varying the magnification from the wide angle end state to the telephoto end state. Meanwhile, by setting the upper limit value of the conditional expression (1) to 1.75, it is possible to secure the advantageous effect more surely. In order to secure the advantageous effect of the variable magnification optical system according to the present embodiment further more surely, it is preferable to set the upper limit value of the conditional expression (1) to 1.70. Furthermore, it is preferable to set the upper limit value of the conditional expression (1) to 1.65, further to 1.60 and further to 1.50.

On the other hand, when the value of (−f1N)/|f1| is equal to or falls below the lower limit of the conditional expression (1) of the variable magnification optical system of the present embodiment, refractive power of a lens having the strongest negative refractive power in lenses in the first lens group becomes strong, and it becomes difficult to suppress coma aberration and other various aberrations. Meanwhile, if the lower limit value of the conditional expression (1) is set to 0.65, it is possible to secure the advantageous effect more surely. In order to secure the advantageous effect of the variable magnification optical system according to the present embodiment further more surely, it is preferable to set the lower limit value of the conditional expression (1) to 0.70. Furthermore, it is preferable to set the lower limit value of the conditional expression (1) to 0.75, further to 0.80 and further to 0.85.

The conditional expression (2) defines a ratio of a back focus of the variable magnification optical system in the wide angle end state relative to a focal length of the variable magnification optical system in the wide angle end state. With satisfying the conditional expression (2), the variable magnification optical system according to the present embodiment can correct effectively coma aberration and other various aberrations in the wide angle end state.

Meanwhile, the term “back focus” means a distance along the optical axis from the most image side lens surface to the image plane.

When the value of BFw/fw is equal to or exceeds the upper limit of the conditional expression (2) of the variable magnification optical system of the present embodiment, the back focus in the wide angle end state relative to the focal length in the wide angle end state becomes large, and it becomes difficult to correct coma aberration and other various aberrations in the wide angle end state. Meanwhile, by setting the upper limit value of the conditional expression (2) to 1.70, it is possible to secure the advantageous effect of the present embodiment more surely. In order to secure the advantageous effect of the variable magnification optical system according to the present embodiment further more surely, it is preferable to set the upper limit value of the conditional expression (2) to 1.40. Furthermore, it is preferable to set the upper limit value of the conditional expression (2) to 1.20, further to 1.00 and further to 0.80.

On the other hand, when the value of BFw/fw is equal to or falls below the lower limit value of the conditional expression (2) of the variable magnification optical system of the present embodiment, the back focus in the wide angle end state relative to the focal length in the wide angle end state becomes small, and it becomes difficult to correct coma aberration and other various aberrations in the wide angle end state. Further, it becomes difficult also to arrange mechanical members of lens barrel. Meanwhile, by setting the lower limit value of the conditional expression (2) to 0.30 it is possible to secure the advantageous effect more surely. Further, it is preferable to set the lower limit value of the conditional expression (2) to 0.40. Furthermore, it is preferable to set the lower limit value of the conditional expression (2) to 0.45, further to 0.50, further to 0.55 and further to 0.60.

With the above mentioned configurations, it is possible to realize the variable magnification optical system which can suppress superbly variations in aberrations upon varying the magnification from the wide angle end state to the telephoto end state, and variations in various aberrations upon carrying out the focusing from an infinite distance object to a close distance object.

Further, in the variable magnification optical system according to the present embodiment, it is desirable that said object side focusing lens group has positive refractive power. With taking such a configuration, the variable magnification optical system can suppress variations in various aberrations such as spherical aberration and other various aberrations generated upon carrying out the focusing from an infinite distance object to a close distance object.

Further, in the variable magnification optical system according to the present embodiment, it is desirable that the focusing lens group disposed in the most image side in said image side focusing lens group has positive refractive power. With taking such a configuration, the variable magnification optical system can suppress variations in spherical aberration and other various aberrations generated upon carrying out the focusing from an infinite distance object to a close distance object.

Further, in the variable magnification optical system according to the present embodiment, it is desirable that said object side focusing lens group is composed of one or two lens components. With this configuration, the focusing lens group may be downsized and reduced in weight.

Further, in the variable magnification optical system according to the present embodiment, it is desirable that said image side focusing lens group is composed of one or two lens components. With this configuration, the focusing lens group may be downsized and reduced in weight.

Further, in the variable magnification optical system according to the present embodiment, it is desirable that said first lens group is fixed upon carrying out the focusing. With this configuration, lens barrel may be prevented from being large sized.

It is desirable that the variable magnification optical system according to the present embodiment comprises at least one lens component in a more image side than the focusing lens group disposed in the most image side in said image side focusing lens group, and that the following conditional expression (3) is satisfied:

0.05<(−fRN)/ft<4.50  (3)

where fRN denotes a focal length of the lens having the strongest refractive power in lenses composing said lens components, and ft denotes a focal length of the variable magnification optical system in the telephoto end state.

The variable magnification optical system according to the present embodiment comprises at least one lens component in a more image side than the focusing lens group disposed in the most image side in the image side focusing lens group, thereby it being possible to suppress variations in coma aberration generated upon carrying out the focusing from the infinite distance object to the close distance object. Meanwhile, the term “lens component” means a single lens or a cemented lens.

The conditional expression (3) defines a ratio of a focal length of the lens having the strongest negative refractive power, in lenses composing the lens components located in more image side than the focusing lens group disposed in the most image side in the image side focusing lens group, relative to a focal length of the variable magnification optical system in the telephoto end state.

With satisfying the conditional expression (3), the variable magnification optical system according to the present embodiment can suppress variations in coma aberration and other various aberrations upon carrying out focusing from the infinite distance object to the close distance object.

When the value of (−fRN)/ft is equal to or exceeds the upper limit value of the conditional expression (3) of the variable magnification optical system according to the present embodiment, refractive power of the lens having the strongest negative refractive power, in lenses composing the lens components disposed in the more image side than the focusing lens group disposed in the most image side in the image side focusing lens group, becomes weak, and it becomes difficult to suppress variation in coma aberration caused upon carrying out the focusing from the infinite distance object to the close distance object.

Meanwhile, by setting the upper limit value of the conditional expression (3) to 4.20, it is possible to secure the advantageous effect more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the upper limit value of the conditional expression (3) to 3.90. Furthermore, it is preferable to set the upper limit value of the conditional expression (3) to 3.50, further to 3.00 and further to 2.50.

On the other hand, when the value of (−fRN)/ft in the conditional expression (3) of the variable magnification optical system according to the present embodiment, is equal to or falls below the lower limit value, refractive power of the lens having the strongest negative refractive power, in lenses composing the lens components located in the more image side than the focusing lens group disposed in the most image side in the image side focusing lens group, becomes strong, and it becomes difficult to suppress variation in coma aberration caused upon carrying out the focusing from the infinite distance object to the close distance object.

Meanwhile, by setting the lower limit value of the conditional expression (3) to 0.06, it is possible to secure the advantageous effect more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the lower limit value of the conditional expression (3) to 0.07. Furthermore, it is preferable to set the lower limit value of the conditional expression (3) to 0.10, further to 0.14, further to 0.65, further to 0.75, further to 0.85 and further to 0.95.

Further, in the variable magnification optical system according to the present embodiment, it is desirable that the following conditional expression (4) is satisfied:

MTF1/MTF2<5.0  (4)

where MTF1 denotes an absolute value of a movement amount of said object side focusing lens group upon carrying out focusing from the infinite distance object to the close distance object in the tele photo end state, and MTF2 denotes an absolute value of a movement amount of the focusing lens group disposed in the most object side in said image side focusing lens group, upon carrying out the focusing from the infinite distance object to the close distance object in the tele photo end state.

The conditional expression (4) defines a ratio of an absolute value of a movement amount of the object side focusing lens group upon carrying out focusing from the infinite distance object to the close distance object in the tele photo end state relative to an absolute value of a movement amount of the focusing lens group disposed in the most object side in said image side focusing lens group, upon carrying out the focusing from the infinite distance object to the close distance object in the tele photo end state. With satisfying the conditional expression (4), the variable magnification optical system according to the present embodiment can effectively suppress variation in spherical aberration upon carrying out the focusing from the infinite distance object to the close distance object.

When the value of MTF1/MTF2 is equal to or exceeds the upper limit value of the conditional expression (4) of the variable magnification optical system according to the present embodiment, an amount of movement of the object side lens group relative to the focusing lens group disposed in the most object side in the image side focusing lens group, becomes too large, and it becomes difficult to correct variation in spherical aberration caused upon carrying out the focusing from the infinite distance object to the close distance object.

Meanwhile, by setting the upper limit value of the conditional expression (4) to 4.7, it is possible to secure the advantageous effect more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the upper limit value of the conditional expression (4) to 4.5. Furthermore, it is preferable to set the upper limit value of the conditional expression (4) to 4.0, further to 3.5, further to 2.8, and further to 2.4.

In order to secure the advantageous effect of the present embodiment surely, it is preferable that the conditional expression (4) satisfies the following expression:

2.0<MTF1/MTF2<5.0

By setting the lower limit value of the conditional expression (4) to 2.0, it is possible to suppress further effectively variation in spherical aberration upon carrying out the focusing.

Further, in the variable magnification optical system according to the present embodiment, it is desirable that at least one focusing lens group of said object side focusing lens group and said image side focusing lens group comprises at least one lens having negative refractive power and that the following conditional expression (5) is satisfied:

0.45<(−fFN)/|fF|<1.70  (5)

where fFN denotes a focal length of the lens having the strongest negative refractive power in lenses in said object side focusing lens group and said image side focusing lens group, and fF denotes a focal length of the focusing lens group having the strongest refractive power, in said object side focusing lens group and said image side focusing lens group.

In the variable magnification optical system according to the present embodiment, at least one focusing lens group in said object side focusing lens group and said image side focusing lens group comprises at least one lens having negative refractive power, thereby it being possible to suppress variations in spherical aberration as well as chromatic aberration upon carrying out focusing from the infinite distance object to the close distance object.

The conditional expression (5) defines a ratio of a focal length of the lens having the strongest negative refractive power in the lenses in the object side focusing lens group and the image side focusing lens group, relative to a focal length of the focusing lens group having the strongest refractive power in said object side focusing lens group and said image side focusing lens group. With satisfying the conditional expression (5), the variable magnification optical system according to the present embodiment can suppress variations in spherical aberration and other various aberrations, upon carrying out focusing from the infinite distance object to the close distance object.

When the value of (−fFN)/|fF| is equal to or exceeds the upper limit value of the conditional expression (5) of the variable magnification optical system according to the present embodiment, refractive power of the focusing lens group having the strongest refractive power, in the object side focusing lens group and the image side focusing lens group, becomes too strong, and it becomes difficult to suppress variations in spherical aberration and other various aberrations caused upon carrying out the focusing from the infinite distance object to the close distance object. Meanwhile, by setting the upper limit value of the conditional expression (5) to 1.60, it is possible to secure the advantageous effect of the present embodiment more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the upper limit value of the conditional expression (5) to 1.50. Furthermore, it is preferable to set the upper limit value of the conditional expression (5) to 1.40, further to 1.30 and further to 1.25.

On the other hand, when the value of (−fFN)/|fF| in the conditional expression (5) of the variable magnification optical system according to the present embodiment, is equal to or falls below the lower limit value, refractive power of the lens having the strongest negative refractive power, in the lenses in the object side focusing lens group and the image side focusing lens group, becomes too strong, and it becomes difficult to suppress variations in spherical aberration and other various aberrations caused upon carrying out the focusing from the infinite distance object to the close distance object. Meanwhile, by setting the lower limit value of the conditional expression (5) to 0.47, it is possible to secure the advantageous effect of the present embodiment more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the lower limit value of the conditional expression (5) to 0.50. Furthermore, it is preferable to set the lower limit value of the conditional expression (5) to 0.54 and further to 0.60.

Further, in the variable magnification optical system according to the present embodiment, it is desirable that at least one focusing lens group in said object side focusing lens group and said image side focusing lens group, comprises at least one lens having negative refractive power, and that the following conditional expression (6) is satisfied:

0.65<nP/nN<1.10  (6)

where nP denotes refractive index of the lens having the strongest positive refractive power in lenses in said object side focusing lens group and said image side focusing lens group, and nN denotes refractive index of the lens having the strongest negative refractive power in the lenses in said object side focusing lens group and said image side focusing lens group.

In the variable magnification optical system according to the present embodiment, at least one focusing lens group in the object side focusing lens group and the image side focusing lens group, comprises at least one lens having negative refractive power, thereby it being possible to suppress variations in spherical aberration as well as chromatic aberration caused upon carrying out the focusing from the infinite distance object to the close distance object.

The conditional expression (6) defines a ratio of refractive index of the lens having the strongest positive refractive power in lenses in the object side focusing lens group and the image side focusing lens group, relative to refractive index of the lens having the strongest negative refractive power in the lenses in the object side focusing lens group and the image side focusing lens group.

With satisfying the conditional expression (6), the variable magnification optical system according to the present embodiment can suppress variations in spherical aberration and other various aberrations upon carrying out focusing from the infinite distance object to the close distance object.

When the value of nP/nN is equal to or exceeds the upper limit value of the conditional expression (6) of the variable magnification optical system according to the present embodiment, positive refractive power of the lens having the strongest positive refractive power, in the lenses in the object side focusing lens group and the image side focusing lens group becomes too strong, and it becomes difficult to suppress variations in spherical aberration and other various aberrations caused upon carrying out the focusing from the infinite distance object to the close distance object.

Meanwhile, by setting the upper limit value of the conditional expression (6) to 1.05, it is possible to secure the advantageous effect of the present embodiment more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the upper limit value of the conditional expression (6) to 1.03. Furthermore, it is preferable to set the upper limit value of the conditional expression (6) to 1.00 and further to 0.95.

On the other hand, when the value of nP/nN in the conditional expression (6) of the variable magnification optical system according to the present embodiment, is equal to or falls below the lower limit value, negative refractive power of the lens having the strongest negative refractive power, in lenses in the object side focusing lens group and said image side focusing lens group, becomes too strong, and it becomes difficult to suppress variations in spherical aberration and other various aberrations caused upon carrying out the focusing from the infinite distance object to the close distance object. Meanwhile, by setting the lower limit value of the conditional expression (6) to 0.67, it is possible to secure the advantageous effect more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the lower limit value of the conditional expression (6) to 0.70. Furthermore, it is preferable to set the lower limit value of the conditional expression (6) to 0.75, further to 0.80, and further to 0.83.

In the variable magnification optical system according to the present embodiment, it is desirable that the following conditional expression (7) is satisfied:

0.40<|fF1|/|f1|<2.60  (7)

where fF1 denotes a focal length of said object side focusing lens group, and f1 denotes a focal length of said first lens group.

The conditional expression (7) defines a ratio of a focal length of the object side focusing lens group, relative to a focal length of the first lens group. With satisfying the conditional expression (7), the variable magnification optical system according to the present embodiment can effectively suppress variations in spherical aberration and other various aberrations upon carrying out the focusing from the infinite distance object to the close distance object, and can suppress variations in spherical aberration and other various aberrations upon varying the magnification from the wide angle end state to the telephoto end state.

When the value of |fF1|/|f1| is equal to or exceeds the upper limit value of the conditional expression (7) of the variable magnification optical system according to the present embodiment, refractive power of the first lens group becomes strong, and it becomes difficult to suppress variations in spherical aberration and other various aberrations caused upon varying the magnification from the wide angle end state to the telephoto end state. Meanwhile, by setting the upper limit value of the conditional expression (7) to 2.55, it is possible to secure the advantageous effect more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the upper limit value of the conditional expression (7) to 2.50. Furthermore, it is preferable to set the upper limit value of the conditional expression (7) to 2.30, and further to 2.10.

On the other hand, when the value of |fF1|/|f1| in the conditional expression (7) of the variable magnification optical system according to the present embodiment, is equal to or falls below the lower limit value, refractive power of the object side focusing lens group, becomes strong, and it becomes difficult to suppress variations in spherical aberration and other various aberrations upon carrying out the focusing from the infinite distance object to the close distance object. Meanwhile, by setting the lower limit value of the conditional expression (7) to 0.45, it is possible to secure the advantageous effect more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the lower limit value of the conditional expression (7) to 0.47. Furthermore, it is preferable to set the lower limit value of the conditional expression (7) to 0.50, further to 0.55, and further to 0.60.

In the variable magnification optical system according to the present embodiment, it is desirable that the following conditional expression (8) is satisfied:

0.20<|fF2|/|f1|<3.80  (8)

where fF2 denotes a focal length of the focusing lens group disposed in the most image side in said image side focusing lens group, and f1 denotes a focal length of said first lens group.

The conditional expression (8) defines a ratio of a focal length of the focusing lens group disposed in the most image side in the image side focusing lens group, relative to a focal length of the first lens group. With satisfying the conditional expression (8), the variable magnification optical system according to the present embodiment can effectively suppress variations in spherical aberration and other various aberrations upon carrying out the focusing from the infinite distance object to the close distance object, and can suppress variations in spherical aberration and other various aberrations upon varying the magnification from the wide angle end state to the telephoto end state.

When the value of |fF2|/|f1| is equal to or exceeds the upper limit value of the conditional expression (8) of the variable magnification optical system according to the present embodiment, refractive power of the first lens group becomes strong, and it becomes difficult to suppress variations in spherical aberration and other various aberrations caused upon varying the magnification from the wide angle end state to the telephoto end state. Meanwhile, by setting the upper limit value of the conditional expression (8) to 3.60, it is possible to secure the advantageous effect more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the upper limit value of the conditional expression (8) to 3.40. Furthermore, it is preferable to set the upper limit value of the conditional expression (8) to 3.00, further to 2.50 and further to 1.90.

On the other hand, when the value of |fF2|/|f1| in the conditional expression (8) of the variable magnification optical system according to the present embodiment, is equal to or falls below the lower limit value, refractive power of the focusing lens group disposed in the most image side in the image side focusing lens group, becomes strong, and it becomes difficult to suppress variations in spherical aberration and other various aberrations upon carrying out the focusing from the infinite distance object to the close distance object. Meanwhile, by setting the lower limit value of the conditional expression (8) to 0.25, it is possible to secure the advantageous effect of the present embodiment more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the lower limit value of the conditional expression (8) to 0.28. Furthermore, it is preferable to set the lower limit value of the conditional expression (8) to 0.50, further to 0.70, further to 0.90 and further to 1.20.

Further, in the variable magnification optical system according to the present embodiment, it is desirable that the object side focusing lens group consists of, in order from the object side, a lens having positive refractive power and a lens having negative refractive power. With taking such a configuration, the variable magnification optical system can suppress effectively variations in spherical aberration and other various aberrations generated upon carrying out the focusing from an infinite distance object to a close distance object.

It is desirable that the variable magnification optical system according to the present embodiment, comprises an aperture stop, and said object side focusing lens group is disposed in a more image side than said aperture stop. With this configuration, the focusing lens group may be reduced in weight.

Further, in the variable magnification optical system according to the present embodiment, it is desirable that the following conditional expression (9) is satisfied:

0.10<|fF1|/ft<3.00  (9)

where fF1 denotes a focal length of said object side focusing lens group, and ft denotes a focal length of said variable magnification optical system in the telephoto end state.

The conditional expression (9) defines a ratio of a focal length of the object side focusing lens group relative to a focal length of the variable magnification optical system in the telephoto end state. With satisfying the conditional expression (9), the variable magnification optical system according to the present embodiment can suppress variations in spherical aberration and other various aberrations upon carrying out the focusing from the infinite distance object to the close distance object.

When the value of |fF1|/ft is equal to or exceeds the upper limit value of the conditional expression (9) of the variable magnification optical system according to the present embodiment, the focal length of the object side focusing lens group, becomes large, and an amount of movement of the object side focusing lens group upon carrying out the focusing from the infinite distance object to the close distance object becomes too large and it becomes difficult to correct variations in spherical aberration and other various aberrations upon carrying out the focusing from the infinite distance object to the close distance object. Meanwhile, by setting the upper limit value of the conditional expression (9) to 2.80, it is possible to secure the advantageous effect more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the upper limit value of the conditional expression (9) to 2.60. Furthermore, it is preferable to set the upper limit value of the conditional expression (9) to 2.20, further to 1.90 and further to 1.60.

On the other hand, when the value of |fF1|/ft in the conditional expression (9) of the variable magnification optical system according to the present embodiment, is equal to or falls below the lower limit value, refractive power of the object side focusing lens group becomes strong, and it becomes difficult to suppress variations in spherical aberration and other various aberrations upon carrying out the focusing from the infinite distance object to the close distance object. Meanwhile, by setting the lower limit value of the conditional expression (9) to 0.12, it is possible to secure the advantageous effect more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the lower limit value of the conditional expression (9) to 0.15.

Further, in the variable magnification optical system according to the present embodiment, it is desirable that the following conditional expression (10) is satisfied:

0.10<|fF2|/ft<3.00  (10)

where fF2 denotes a focal length of the focusing lens group disposed in the most image side in said image side focusing lens group, and ft denotes a focal length of said variable magnification optical system in the telephoto end state.

The conditional expression (10) defines a ratio of a focal length of the focusing lens group disposed in the most image side in said image side focusing lens group relative to a focal length of said variable magnification optical system in the telephoto end state. With satisfying the conditional expression (10), the variable magnification optical system according to the present embodiment can effectively suppress variations in spherical aberration and other various aberrations upon carrying out the focusing from the infinite distance object to the close distance object.

When the value of |fF2|/ft is equal to or exceeds the upper limit value of the conditional expression (10) of the variable magnification optical system according to the present embodiment, the focal length of the focusing lens group disposed in the most image side in the image side focusing lens group, becomes large, and the amount of the movement of the focusing lens group disposed in the most image side upon carrying out the focusing from the infinite distance object to the close distance object, becomes too large, thereby it becoming difficult to correct variations in spherical aberration and other various aberrations upon carrying out the focusing from the infinite distance object to the close distance object. Meanwhile, by setting the upper limit value of the conditional expression (10) to 2.80, it is possible to secure the advantageous effect of the present embodiment more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the upper limit value of the conditional expression (10) to 2.60.

On the other hand, when the value of |fF2|/ft| in the conditional expression (10) of the variable magnification optical system according to the present embodiment, is equal to or falls below the lower limit value, refractive power of the focusing lens group disposed in the most image side in the image side focusing lens group, becomes strong, and it becomes difficult to suppress variations in spherical aberration and other various aberrations upon carrying out the focusing from the infinite distance object to the close distance object. Meanwhile, by setting the lower limit value of the conditional expression (10) to 0.12, it is possible to secure the advantageous effect more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the lower limit value of the conditional expression (10) to 0.15.

In the variable magnification optical system according to the present embodiment, it is desirable that the following conditional expression (11) is satisfied:

|βWF1|/|βWF2|<4.00  (11)

where |WF1 denotes a transverse magnification of said object side focusing lens group in the wide angle end state upon focusing on an infinite distance object, and βWF2 denotes a transverse magnification of the focusing lens group disposed in the most object side in said image side focusing lens group in the wide angle end state upon focusing on the infinite distance object.

The conditional expression (11) defines a ratio of a transverse magnification of the object side focusing lens group in the wide angle end state upon focusing on an infinite distance object, relative to a transverse magnification of the focusing lens group disposed in the most object side in the image side focusing lens group in the wide angle end state upon focusing on the infinite distance object. With satisfying the conditional expression (11), the variable magnification optical system according to the present embodiment can effectively suppress variations in spherical aberration and other various aberrations upon carrying out the focusing in the wide angle end state from the infinite distance object to the close distance object.

When the value of |βWF1|/|βWF2| is equal to or exceeds the upper limit value of the conditional expression (11) of the variable magnification optical system according to the present embodiment, the transverse magnification of the object side focusing lens group in the wide angle end state upon focusing on an infinite distance object, relative to the transverse magnification of the focusing lens group disposed in the most object side in the image side focusing lens group in the wide angle end state upon focusing on the infinite distance object, becomes large, and it becomes difficult to suppress variations in spherical aberration and other various aberrations, upon carrying out the focusing in the wide angle end state from the infinite distance object to the close distance object.

Meanwhile, by setting the upper limit value of the conditional expression (11) to 3.50, it is possible to secure the advantageous effect of the present embodiment more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the upper limit value of the conditional expression (11) to 3.00. Furthermore, it is preferable to set the upper limit value of the conditional expression (11) to 2.50, further to 2.00, further to 1.50 and further to 1.20.

In the variable magnification optical system according to the present embodiment, it is desirable that the following conditional expression (12) is satisfied:

∥βRw|/|βRt|<4.00  (12)

where βRw denotes a composite transverse magnification from said object side focusing lens group to the image plane in the wide angle end state upon focusing on an infinite distance object, and βRt denotes a composite transverse magnification from the object side focusing lens group to the image plane in the telephoto end state upon focusing on the infinite distance object.

The conditional expression (12) defines a ratio of a composite transverse magnification from the object side focusing lens group to the image plane in the wide angle end state upon focusing on an infinite distance object, relative to a composite transverse magnification from the object side focusing lens group to the image plane in the telephoto end state upon focusing on the infinite distance object. With satisfying the conditional expression (12), the variable magnification optical system according to the present embodiment can effectively suppress variations in spherical aberration and other various aberrations upon carrying out the focusing in the wide angle end state from the infinite distance object to the close distance object.

When the value of |βWF1|/|βWF2| is equal to or exceeds the upper limit value of the conditional expression (12) of the variable magnification optical system according to the present embodiment, the composite transverse magnification from the object side focusing lens group to the image plane in the wide angle end state upon focusing on an infinite distance object, relative to the composite transverse magnification from the object side focusing lens group to the image plane in the telephoto end state upon focusing on the infinite distance object, becomes large, and it becomes difficult to suppress variations in spherical aberration and other various aberrations upon carrying out the focusing in the wide angle end state from the infinite distance object to the close distance object.

Meanwhile, by setting the upper limit value of the conditional expression (12) to 3.50, it is possible to secure the advantageous effect of the present embodiment more surely. Further, in order to secure the advantageous effect of the present embodiment more surely, it is preferable to set the upper limit value of the conditional expression (12) to 3.00. Furthermore, it is preferable to set the upper limit value of the conditional expression (12) to 2.60, further to 2.20 and further to 1.90.

In the variable magnification optical system according to the present embodiment, it is desirable that the following conditional expression (13) is satisfied:

15.0°<ωw<85.0°  (13)

where ωw denotes a half angle of view of said variable magnification optical system in the wide angle end state.

The conditional expression (13) defines a condition for defining a most optimum value of an angle of view in the wide angle end state. With satisfying the conditional expression (13), the variable magnification optical system according to the present embodiment can superbly correct various aberrations such as coma aberration, distortion, curvature of field and the like, while having wide angle of view.

In order to secure the advantageous effect of the present embodiment surely, it is preferable to set the upper limit value of the conditional expression (13) to 80.0°. Further, it is preferable to set the upper limit value of the conditional expression (13) to 75.0°, further to 70.0° and further to 65.0°.

In order to secure the advantageous effect of the present embodiment surely, it is preferable to set the lower limit value of the conditional expression (13) to 16.0°. Further, it is preferable to set the lower limit value of the conditional expression (13) to 17.0°, further to 35.0°, further to 37.0°, further to 39.0°, further to 40.0°, and further to 42.0°.

Further, an optical apparatus of the present embodiment is equipped with the variable magnification optical system having the above described configuration, so it is possible to realize an optical apparatus which can suppress variations in aberrations upon varying the magnification from the wide angle end state to the telephoto end state, and which can suppress superbly variations in aberrations upon carrying out the focusing from the infinite distance object to the close distance object.

Further, a method for manufacturing a variable magnification optical system according to the present embodiment, is a method for manufacturing a variable magnification optical system which comprises, in order from an object side, a first lens group and a plurality of lens groups; comprising the steps of:

constructing such that, upon varying a magnification, a distance between said first lens group and said plurality of lens groups is varied, and distances between respective lens groups in said plurality of lens groups are varied;

constructing such that said plurality of lens groups comprise an object side focusing lens group which is moved upon carrying out focusing and at least one image side focusing lens group disposed in a more image side than said object side focusing lens group and moved with a trajectory differing from that of said object side focusing lens group upon carrying out the focusing; and

constructing such that the following conditional expressions (1) and (2) are satisfied:

0.60<(−f1N)/|f1|<1.80  (1)

0.2<BFw/fw<2.0  (2)

where f1N denotes a focal length of a lens which has a strongest negative refractive power in lenses in said first lens group, f1 denotes a focal length of said first lens groups, BFw denotes a back focus of said variable magnification optical system in the wide angle end state, and fw denotes a focal length of said variable magnification optical system in the wide angle end state.

Thus, it is possible to manufacture the variable magnification optical system which can suppress superbly variations in aberrations upon varying the magnification from the wide angle end state to the telephoto end state and upon carrying out the focusing from the infinite distance object to the close distance object.

Hereinafter, the variable magnification optical systems relating to numerical examples of the present embodiment will be explained with reference to the accompanying drawings.

First Example

FIG. 1 is a sectional view of a variable magnification optical system according to a First Example. Meanwhile, in FIG. 1 and FIG. 4, FIG. 7, FIG. 10, FIG. 13, FIG. 16, FIG. 19, FIG. 22, FIG. 25, FIG. 28, and FIG. 31 described later, arrows show movement trajectories of the respective lens groups upon varying magnification from a wide angle end state (W) to a telephoto end state (T).

The variable magnification optical system according to the present Example is composed of, in order from an object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, an aperture stop S, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power and a seventh lens group G7 having negative refractive power.

The first lens group G1 consists of, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a cemented negative lens constructed by a double concave negative lens L12 cemented with a positive meniscus lens L13 having a convex surface facing the object side.

The second lens group G2 consists of a cemented positive lens constructed by a double convex positive lens L21 cemented with a negative meniscus lens L22 having a concave surface facing the object side.

The third lens group G3 consists of a cemented positive lens constructed by a negative meniscus lens L31 having a convex surface facing the object side cemented with a double convex positive lens L32.

The fourth lens group G4 consists of, in order from the object side, a cemented negative lens constructed by a double concave negative lens L41 cemented with a positive meniscus lens L42 having a convex surface facing the object side, and a positive meniscus lens L43 having a convex surface facing the object side.

The fifth lens group G5 consists of a cemented positive lens constructed by a double convex positive lens L51 cemented with a negative meniscus lens L52 having a concave surface facing the object side.

The sixth lens group G6 consists of a double convex positive lens L61.

The seventh lens group G7 consists of a negative meniscus lens L71 having a concave surface facing the object side.

In the variable magnification optical system according to the present Example, upon varying magnification between the wide angle end state and the telephoto end state, all lens groups of the first lens group G1 to the seventh lens group G7 are moved along the optical axis such that a distance between the first lens group G1 and the second lens group G2, a distance between the second lens group G2 and the third lens group G3, a distance between the third lens group G3 and the fourth lens group G4, a distance between the fourth lens group G4 and the fifth lens group G5, a distance between the fifth lens group G5 and the sixth lens group G6 and a distance between the sixth lens group G6 and the seventh lens group G7, are varied.

In the optical system according to the present Example, focusing from an infinite distance object to a close distance object is carried out by moving, as focusing lens groups, the fifth lens group G5 along the optical axis toward the object side and the sixth lens group G6 along the optical axis toward the object side with a different trajectory from that of the fifth lens group G5.

Table 1 below shows various values of the variable magnification optical system relating to the present Example.

In Table 1, “f” denotes a focal length, and “BF” denotes a back focus, that is, a distance along the optical axis from the most image side lens surface to the image plane I.

In [Surface Data], “m” denotes an order of an optical surface counted from the object side, “r” denotes a radius of curvature, “d” denotes a surface-to-surface distance, that is, an interval from an n-th surface to an (n+1)-th surface, where n is an integer, “nd” denotes refractive index for d-line (wavelength λ=587.6 nm) and “νd” denotes an Abbe number for d-line (wavelength λ=587.6 nm). Further, “OP” denotes an object surface, “Variable” denotes a variable surface-to-surface distance, “S” denotes an aperture stop, and “I” denotes an image plane. Meanwhile, radius of curvature r=∞ denotes a plane surface, and refractive index of the air nd=1.00000 is omitted. In addition, an aspherical surface is expressed by attaching “*” to the surface number, and in the column of the radius of curvature “r”, a paraxial radius of curvature is shown.

In [Aspherical Data], with respect to an aspherical surface shown in [Surface Data], an aspherical surface coefficient and a conical coefficient are shown in the case where the aspherical surface is exhibited by the following expression:

x=(h ² /r)/[1+{1−κ(h/r)²}^(1/2)]+A4h ⁴ +A6h ⁶ +A8h ⁸ +A10h ¹⁰

where “h” denotes a height in the direction perpendicular to the optical axis, “x” denotes a sag amount that is a distance along the optical axis from the tangent surface at the vertex of the aspherical surface to the aspherical surface at the height “h”; “κ” denotes a conical coefficient; “A4”, “A6”, “A8” and “A10” denote respective aspherical coefficients, and “r” denotes a paraxial radius of curvature that is a radius of curvature of a reference sphere. “E-n”, where n is an integer, denotes “×10^(−n)”, for example, “1.234E-05” denotes “1.234×10⁻⁵”. Second order aspherical coefficient “A2” is 0 and omitted.

In [Various Data], “f” denotes a total length of the entire lens system, “FNO” denotes an F-number, “2ω” denotes an angle of view (unit “°”), “Ymax” denotes a maximum image height, and “TL” denotes a total length of the variable magnification optical system according to the present Example, that is, a distance along the optical axis from the first lens surface to the image plane I, “β” denotes an imaging magnification between the object and the image, “d0” denotes a distance along the optical axis from the object plane OP to the first surface, d0=0.000 corresponds to “upon focusing on an infinite distance object”, d=641.690 corresponds to “upon focusing on a close distance object”, and “dn” denotes a variable distance from the n-th surface to the (n+1)-th surface. Meanwhile, regarding “f” and “β”, “f” denotes an infinite distance and “β” denotes a close distance, “W” denotes a wide angle end state, “M” denotes an intermediate focal length state, “T” denotes a tele photo end state.

In [Lens Group Data], a starting surface ST and a focal length f of each lens group are shown.

In [Values for Conditional Expressions], values corresponding to respective conditional expressions of the variable magnification optical system according to the present Example, are shown.

It is noted, here, that “mm” is generally used for the unit of length such as the focal length f, the radius of curvature r and the unit for other lengths shown in Table 1. However, since similar optical performance can be obtained by an optical system proportionally enlarged or reduced, the unit is not necessarily to be limited to “mm”.

Meanwhile, the explanation of reference symbols in Table 1 described above, is the same in Tables for the other Examples described herein later.

TABLE 1 First Example [Surface Data] m r OP ∞ d nd νd  1 270.0000 2.900 1.74389 49.53  *2 33.2562 13.215  3 −1900.2102 2.100 1.59349 67.00  4 35.8236 7.700 2.00100 29.12  5 79.6938 Variable  6 271.3181 7.400 1.83481 42.73  7 −36.9149 1.500 1.75520 27.57  8 −164.0000 Variable  9 39.7511 1.500 1.85000 27.03  10 25.6246 10.800 1.59319 67.90  11 −134.6401 Variable 12 (S) ∞ 2.350  13 −65.9523 1.300 1.80100 34.92  14 18.5797 4.700 1.90366 31.27  15 51.6074 0.919  16 45.9293 2.500 1.94595 17.98  17 120.0000 Variable  18 47.5350 7.100 1.48749 70.31  19 −24.2409 1.300 1.69895 30.13  20 −74.7188 Variable  21 113.0000 4.200 1.58913 61.15 *22 −108.0000 Variable *23 −30.5616 1.500 1.58913 61.15  24 −81.9388 BF I ∞ [Aspherical Data] m:2 κ = 0.0000 A4 = 2.97162E−06 A6 = 1.62510E−09 A8= 2.42658E−13 A10 = 4.56491E−16 A12 = 8.02650E−19 m:22 κ = 1.0000 A4 = 8.43912E−06 A6 = 6.68890E−10 A8 = 1.69267E−11 A10 = −5.36609E−14 m:23 κ = 1.0000 A4 = 8.13845E−06 A6 = −4.05875E−09 A8 = 1.66491E−11 A10 = −5.84964E−14 [Various Data] Variable magnification ratio 2.99 W M T f 22.7 50.0 67.9 FNO 2.92 2.92 2.92 2ω 91.10 45.68 33.64 Ymax 19.32 21.60 21.60 TL 188.45 157.95 163.95 BF 11.75 20.19 25.26 W M T W M T f, β 22.700 50.000 67.900 −0.033 −0.033 −0.033 d0  0.000 0.000 0.000 641.690 1469.10 2002.79 d5  63.985 10.998 3.100 63.985 10.998 3.100 d8  1.000 1.763 1.000 1.000 1.763 1.000 d11 1.900 12.973 26.707 1.900 12.973 26.707 d17 20.431 12.752 12.052 20.013 11.839 10.654 d20 8.701 16.480 16.780 8.112 16.125 16.831 d22 7.699 9.815 6.069 8.705 11.084 7.415 [Lens Group Data] Group ST f 1 1 −46.132 2 6 102.733 3 9 64.434 4 12 −89.031 5 18 92.237 6 21 94.399 7 23 −83.639 [Values for Conditional Expressions]  (1) (−f1N)/|f1| = 1.111  (2) BFw/fw = 0.518  (3) (−fRN)/ft = 1.232  (4) MTF1/MTF2 = 1.038  (5) (−fFN)/|fF| = 0.563  (6) nP/nN = 0.876  (7) |fF1|/|f1| = 1.999  (8) |fF2|/|f1| = 2.046  (9) |fF1|/ft = 1.358 (10) |fF2|/ft = 1.390 (11) |βWF1|/|βWF2| = 0.719 (12) |βRw|/|βRt| = 1.616 (13) ωw = 45.55°

FIGS. 2A, 2B and 2C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the First Example.

FIGS. 3A, 3B and 3C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the First Example.

In the graphs showing aberrations as drawn in FIG. 2 and FIG. 3, “FNO” denotes an F-number, “NA” denotes a numerical aperture, and “Y” denotes an image height. In graphs showing spherical aberration, the value of the numerical aperture or F-number corresponding to the maximum aperture is shown. In graphs showing astigmatism and distortion, the maximum value of the image height is shown. In graphs showing coma aberration, the value for each image height is shown. “d” denotes d-line (wavelength λ=587.6 nm), and “g” denotes g-line (wavelength λ=435.8 nm). In graphs showing astigmatism, a solid line indicates a sagittal image plane, and a broken line indicates a meridional image plane. Meanwhile, in graphs showing various aberrations in the other Examples as described below, the same symbols as in the present Example are employed.

As is apparent from the above-mentioned graphs showing various aberrations, the variable magnification optical system relating to the present Example can correct superbly various aberrations over the wide angle end state to the telephoto end state and has excellent imaging performance, and further has excellent imaging performance even upon focusing on a close distance object.

Second Example

FIG. 4 is a view showing a lens configuration of a variable magnification optical system according to a Second Example.

The variable magnification optical system according to the present Example is composed of, in order from an object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, an aperture stop S, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power.

The first lens group G1 consists of, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, and a cemented negative lens constructed by a negative meniscus lens L12 having a convex surface facing the object side cemented with a positive meniscus lens L13 having a convex surface facing the object side.

The second lens group G2 consists of, in order from the object side, a cemented positive lens constructed by a double convex positive lens L21 cemented with a negative meniscus lens L22 having a concave surface facing the object side, and a cemented positive lens constructed by a negative meniscus lens L23 having a convex surface facing the object side cemented with a double convex positive lens L24.

The third lens group G3 consists of, in order from the object side, a double concave negative lens L31, and a cemented positive lens constructed by a double concave negative lens L32 cemented with a double convex positive lens L33.

The fourth lens group G4 consists of a cemented positive lens constructed by a double convex positive lens L41 cemented with a negative meniscus lens L42 having a concave surface facing the object side.

The fifth lens group G5 consists of a double convex positive lens L51.

The sixth lens group G6 consists of a negative meniscus lens L61 having a concave surface facing the object side.

In the variable magnification optical system according to the present Example, upon varying magnification between the wide angle end state and the telephoto end state, all lens groups of the first lens group G1 to the sixth lens group G6 are moved along the optical axis such that a distance between the first lens group G1 and the second lens group G2, a distance between the second lens group G2 and the third lens group G3, a distance between the third lens group G3 and the fourth lens group G4, a distance between the fourth lens group G4 and the fifth lens group G5, and a distance between the fifth lens group G5 and the sixth lens group G6, are varied.

In the optical system according to the present Example, focusing from an infinite distance object to a close distance object is carried out by moving, as focusing lens groups, the fourth lens group G4 along the optical axis toward the object side and the fifth lens group G5 along the optical axis toward the object side with a different trajectory from that of the fourth lens group G4.

Table 2 below shows various values of the variable magnification optical system relating to the present Example.

TABLE 2 Second Example [Surface Data] m r OP ∞ d nd νd  1 217.2239 2.900 1.74389 49.53  *2 30.2414 13.112  3 1223.5572 2.100 1.59349 67.00  4 35.8181 6.436 2.00069 25.46  5 72.5839 Variable  6 128.9112 7.447 1.81600 46.59  7 −39.6982 1.500 1.85000 27.03  8 −142.9408 1.000  9 40.8283 1.500 1.80518 25.45  10 25.0719 10.948 1.60300 65.44  11 −92.3055 Variable 12 (S) ∞ 2.486  13 −55.5201 1.300 1.90265 35.72  14 121.6217 1.190  15 −124.4061 1.300 1.67270 32.18  16 22.4038 6.400 1.80809 22.74  17 −97.2368 Variable  18 62.1388 6.900 1.48749 70.32  19 −23.2151 1.300 1.78472 25.64  20 −50.9732 Variable  21 186.2633 4.200 1.58913 61.15 *22 −79.5614 Variable *23 −33.8149 1.500 1.58913 61.15  24 −131.2649 BF I ∞ [Aspherical Surface Data] m:2 κ = 0.0000 A4 = 3.46899E−06 A6 = 3.81982E−09 A8 = −6.40834E−12 A10 = 1.09738E−14 A12 = −4.82160E−18 m:22 κ = 1.0000 A4 = 6.88818E−06 A6 = −6.09818E−10 A8 = 8.44660E−12 A10 = −2.63571E−14 m:23 κ = 1.0000 A4 = 8.06346E−06 A6 = −8.60497E−09 A8 = 2.28581E−11 A10 = −5.12367E−14 [Various Data] Variable magnification ratio 2.99 W M T f 22.7 50.0 67.9 FNO 2.92 2.92 2.92 2ω 91.24 45.92 33.78 Ymax 19.34 21.60 21.60 TL 188.49 155.49 159.75 BF 16.19 19.69 24.21 W M T W M T f, β 22.700 50.000 67.900 −0.033 −0.033 −0.033 d0  0.000 0.000 0.000 643.745 1470.35 2002.57 d5  63.857 10.035 2.501 63.857 10.035 2.501 d11 2.202 10.972 22.702 2.202 10.972 22.702 d17 19.524 10.852 10.688 19.122 9.959 9.322 d20 8.007 19.445 19.346 7.507 19.082 19.339 d22 5.193 10.974 6.787 6.095 12.231 8.161 [Lens Group Data] Group ST f 1 1 −42.007 2 6 36.073 3 12 −74.292 4 18 96.221 5 21 95.186 6 23 −77.759 [Values for Conditional Expressions]  (1) (−f1N)/|f1| = 1.132  (2) BFw/fw = 0.713  (3) (−fRN)/ft = 1.145  (4) MTF1/MTF2 = 0.995  (5) (−fFN)/|fF| = 0.583  (6) nP/nN = 0.833  (7) |fF1|/|f1| = 2.291  (8) |fF2|/|f1| = 2.266  (9) |fF1|/ft = 1.147 (10) |fF2|/ft = 1.402 (11) |βWF1|/|βWF2| = 0.762 (12) |βRw|/|βRt| = 1.663 (13) ωw = 45.62°

FIG. 5A, FIG. 5B and FIG. 5C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Second Example.

FIG. 6A, FIG. 6B and FIG. 6C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Second Example.

As is apparent from the above-mentioned graphs showing various aberrations, the variable magnification optical system relating to the present Example can correct superbly various aberrations over the wide angle end state to the telephoto end state and has excellent imaging performance, and further has excellent imaging performance even upon focusing on a close distance object.

Third Example

FIG. 7 is a view showing a lens configuration of a variable magnification optical system according to a Third Example of the present application.

The variable magnification optical system according to the present Example is composed of, in order from an object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, an aperture stop S, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power.

The first lens group G1 consists of, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, and a cemented negative lens constructed by a negative meniscus lens L12 having a convex surface facing the object side cemented with a positive meniscus lens L13 having a convex surface facing the object side.

The second lens group G2 consists of a cemented positive lens constructed by a double convex positive lens L21 cemented with a negative meniscus lens L22 having a concave surface facing the object.

The third lens group G3 consists of a cemented positive lens constructed by a negative meniscus lens L31 having a convex surface facing the object side cemented with a double convex positive lens L32.

The fourth lens group G4 consists of a cemented negative lens constructed by a double concave negative lens L41 cemented with a positive meniscus lens L42 having a convex surface facing the object side.

The fifth lens group G5 consists of a cemented positive lens constructed by a double convex positive lens L51 cemented with a negative meniscus lens L52 having a concave surface facing the object side.

The sixth lens group G6 consists of a double convex positive lens L61.

The seventh lens group G7 consists of a negative meniscus lens L71 having a concave surface facing the object side.

In the variable magnification optical system according to the present Example, upon varying magnification between the wide angle end state and the telephoto end state, all lens groups of the first lens group G1 to the seventh lens group G7 are moved along the optical axis such that a distance between the first lens group G1 and the second lens group G2, a distance between the second lens group G2 and the third lens group G3, a distance between the third lens group G3 and the fourth lens group G4, a distance between the fourth lens group G4 and the fifth lens group G5, a distance between the fifth lens group G5 and the sixth lens group G6 and a distance between the sixth lens group G6 and the seventh lens group G7, are varied.

In the variable magnification optical system according to the present Example, focusing from an infinite distance object to a close distance object is carried out by moving, as focusing lens groups, the fifth lens group G5 along the optical axis toward the object side and the sixth lens group G6 along the optical axis toward the object side with a different trajectory from the fifth lens group G5.

Table 3 below shows various values of the variable magnification optical system relating to the present Example.

TABLE 3 Third Example [Surface Data] m r OP ∞ d nd νd  1 259.2015 2.900 1.74389 49.53  *2 30.9799 13.410  3 1201.6909 2.100 1.59349 66.99  4 36.4155 6.936 2.00100 29.14  5 81.5436 Variable  6 124.3745 6.555 1.80400 46.60  7 −55.7538 1.500 1.72825 28.38  8 −633.0468 Variable  9 44.9659 1.500 1.85000 27.03  10 27.3358 10.990 1.59319 67.90  11 −89.5168 Variable 12 (S) ∞ 2.562  13 −58.2664 1.300 1.68893 31.16  14 20.8969 4.742 1.80809 22.74  15 201.5296 Variable  16 52.2605 6.900 1.48749 70.31  17 −26.1209 1.300 1.69895 30.13  18 −72.7540 Variable  19 130.0000 4.200 1.58913 61.15 *20 −100.4826 Variable *21 −44.3630 1.500 1.58913 61.15  22 −412.9422 BF I ∞ [Aspherical Surface Data] m:2 κ = 0.0000 A4 = 3.40299E−06 A6 = 1.78453E−09 A8 = −2.01869E−13 A10 = 1.07948E−15 A12 = 2.74510E−19 m:20 κ = 1.0000 A4 = 8.80591E−06 A6 = −1.07404E−09 A8 = 1.74456E−11 A10 = −2.66494E−14 m:21 κ = 1.0000 A4 = 6.66893E−06 A6 = −5.20154E−09 A8 = 5.00802E−12 A10 = −7.75803E−15 [Various Data] Variable magnification ratio 2.99 W M T f 22.7 50.0 67.9 FNO 2.92 2.92 2.92 2ω 91.30 45.88 33.64 Ymax 19.36 21.60 21.60 TL 188.49 156.49 165.34 BF 14.19 20.41 24.73 W M T W M T f, β 22.700 50.000 67.900 −0.033 −0.033 −0.033 d0  0.000 0.000 0.000 643.522 1473.82 2010.17 d5  64.909 10.197 2.263 64.909 10.197 2.263 d8  1.000 1.000 1.000 1.000 1.000 1.000 d11 2.200 12.573 28.831 2.200 12.573 28.831 d15 22.896 13.304 11.893 22.388 12.281 10.318 d18 8.047 19.430 19.884 7.707 19.294 20.259 d20 6.853 11.181 8.344 7.701 12.340 9.543 [Lens Group Data] Group ST f 1 1 −45.334 2 6 112.275 3 9 63.547 4 12 −98.234 5 16 92.914 6 19 96.856 7 21 −84.494 [Values for Conditional Expressions]  (1) (−f1N)/|f1| = 1.049  (2) BFw/fw = 0.625  (3) (−fRN)/ft = 1.244  (4) MTF1/MFT2 = 1.313  (5) (−fFN)/|fF| = 0.635  (6) nP/nN = 0.876  (7) |fF1|/|f1| = 2.050  (8) |fF2|/|f1| = 2.137  (9) |fF1|/ft = 1.368 (10) |fF2|/ft = 1.426 (11) |βWF1|/|βWF2| = 0.723 (12) |βRw|/|βRt| = 2.084 (13) ωw = 45.65°

FIG. 8A, FIG. 8B and FIG. 8C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Third Example.

FIG. 9A, FIG. 9B and FIG. 9C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Third Example.

As is apparent from the above-mentioned graphs showing aberrations, the variable magnification optical system relating to the present Example can correct superbly various aberrations over the wide angle end state to the telephoto end state and has excellent imaging performance, and further has excellent imaging performance even upon focusing on a close distance object.

Fourth Example

FIG. 10 is a view showing a lens configuration of of a variable magnification optical system according to a Fourth Example of the present application.

The variable magnification optical system according to the present Example is composed of, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power.

The first lens group G1 consists of, in order from the object side, a cemented negative lens constructed by a negative meniscus lens L11 having a convex surface facing the object side cemented with a positive meniscus lens L12 having a convex surface facing the object side, and a positive meniscus lens L13 having a convex surface facing the object side.

The second lens group G2 consists of, in order from the object side, a negative meniscus lens L21 having a convex surface facing the object side, a double concave negative lens L22, a double convex positive lens L23 and a cemented negative lens constructed by a double concave negative lens L24 cemented with a double convex positive lens L25.

The third lens group G3 consists of, in order from the object side, a double convex positive lens L31, a negative meniscus lens L32 having a concave surface facing the object side, a double convex positive lens L33 and a double concave negative lens L34.

The fourth lens group G4 consists of a cemented positive lens constructed by a double convex positive lens L41 cemented with a negative meniscus lens L42 having a concave surface facing the object side.

The fifth lens group G5 consists of a double convex positive lens L51.

The sixth lens group G6 consists of, in order from the object side, a double concave negative lens L61, and a positive meniscus lens L62 having a convex surface facing the object side.

In the variable magnification optical system according to the present Example, upon varying magnification between the wide angle end state and the telephoto end state, all lens groups of the first lens group G1 to the sixth lens group G6 are moved along the optical axis such that a distance between the first lens group G1 and the second lens group G2, a distance between the second lens group G2 and the third lens group G3, a distance between the third lens group G3 and the fourth lens group G4, a distance between the fourth lens group G4 and the fifth lens group G5, and a distance between the fifth lens group G5 and the sixth lens group G6, are varied.

In the variable magnification optical system according to the present Example, focusing from an infinite distance object to a close distance object is carried out by moving, as focusing lens groups, the fourth lens group G4 along the optical axis toward the image side and the fifth lens group G5 along the optical axis toward the object side.

Table 4 below shows various values of the variable magnification optical system relating to the present Example.

TABLE 4 Fourth Example [Surface Data] m r OP ∞ d nd νd  1 1059.3029 1.000 1.84666 23.80  2 88.2318 6.929 1.90265 35.72  3 403.3118 0.200  4 87.3429 6.677 1.81600 46.59  5 899.1448 Variable  *6 145.1405 1.000 1.81600 46.59  7 21.3498 7.013  8 −93.6905 1.000 1.77250 49.62  9 52.8889 0.200  10 40.8152 5.067 1.80518 25.45  11 −74.9610 1.472  12 −36.2791 1.000 1.80400 46.60  13 404.7262 2.056 2.00069 25.46  14 −319.9567 Variable 15 (S) ∞ 0.200  16 88.2548 3.685 1.80400 46.60  17 −54.7142 1.284  18 −30.7175 1.000 1.68893 31.16  19 −74.0526 0.200  20 56.5407 4.903 1.71999 50.27  21 −44.3610 4.918  22 −36.9664 1.000 1.72342 38.03  23 80.5817 Variable  24 573.8232 6.525 1.59349 67.00  25 −22.0116 1.000 1.71736 29.57  26 −42.4849 Variable  27 50.5370 6.205 1.55332 71.68 *28 −153.3313 Variable *29 −95.1749 3.228 1.59551 39.21  30 84.3183 7.544  31 40.5660 7.785 1.59551 39.21  32 180.7170 BF II ∞ [Aspherical Surface Data] m:6 κ = 1.0000 A4 = 1.07708E−06 A6 = −2.41884E−09 A8 = 5.80958E−12 A10 = −5.58700E−15 m:28 κ = 1.0000 A4 = 2.10709E−06 A6 = 4.40633E−09 A8 = −1.52762E−11 A10 = 2.31569E−14 m:29 κ = 1.0000 A4 = −6.15448E−06 A6 = 7.32819E−09 A8 = −2.45254E−11 A10 = 3.72863E−14 [Various Data] Variable magnification ratio 2.99 W M T f 22.7 50.3 67.9 FNO 2.92 2.92 2.92 2ω 91.78 46.78 34.60 Ymax 19.23 21.60 21.60 TL 155.45 174.13 187.93 BF 13.25 21.65 20.92 W M T W M T f, β 22.700 50.288 67.900 −0.033 −0.033 −0.033 d0  0.000 0.000 0.000 638.473 1426.83 1927.07 d5  2.000 25.012 34.560 2.000 25.012 34.560 d14 29.544 7.040 2.000 29.544 7.040 2.000 d23 6.941 4.850 4.000 8.321 5.940 5.254 d26 12.867 12.278 14.712 10.219 9.978 12.178 d28 7.757 20.212 28.652 9.025 21.422 29.932 [Lens Group Data] Group ST f 1 1 131.146 2 6 −21.329 3 15 56.760 4 24 81.373 5 27 69.446 6 29 −1467.881 [Values for Conditional Expressions]  (1) (−f1N)/|f1| = 0.867  (2) BFw/fw = 0.584  (3) (−fRN)/ft = 1.098  (4) MTF1/MTF2 = 0.980  (5) (−fFN)/|fF| = 0.936  (6) nP/nN = 0.928  (7) |fF1|/|f1| = 0.620  (8) |fF2|/|f1| = 0.530  (9) |fF1|/ft = 1.198 (10) |fF2|/ft = 1.023 (11) |βWF1|/|βWF2| = 0.014 (12) |βRw|/ |βRt| = 0.005 (13) ωw = 45.89°

FIG. 11A, FIG. 11B and FIG. 11C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Fourth Example.

FIG. 12A, FIG. 12B and FIG. 12C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Fourth Example.

As is apparent from the above-mentioned graphs showing aberrations, the variable magnification optical system relating to the present Example can correct superbly various aberrations over the wide angle end state to the telephoto end state and has excellent imaging performance, and further has excellent imaging performance even upon focusing on a close distance object.

Fifth Example

FIG. 13 is a view showing a lens configuration of a variable magnification optical system according to a Fifth Example.

The variable magnification optical system according to the present Example is composed of, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power.

The first lens group G1 consists of, in order from the object side, a cemented positive lens constructed by a negative meniscus lens L11 having a convex surface facing the object side cemented with a double convex positive lens L12, and a positive meniscus lens L13 having a convex surface facing the object side.

The second lens group G2 consists of, in order from the object side, a negative meniscus lens L21 having a convex surface facing the object side, a negative meniscus lens L22 having a concave surface facing the object side, a positive meniscus lens L23 having a concave surface facing the object side, and a negative meniscus lens L24 having a concave surface facing the object side.

The third lens group G3 consists of, in order from the object side, a positive meniscus lens L31 having a convex surface facing the object side, a double convex positive lens L32, and a cemented positive lens constructed by a double convex positive lens L33 cemented with a negative meniscus lens L34 having a concave surface facing the object side.

The fourth lens group G4 consists of, in order from the object side, a double concave negative lens L41 and a double convex positive lens L42.

The fifth lens group G5 consists of a double convex positive lens L51.

The sixth lens group G6 consists of, in order from the object side, a double concave negative lens L61 and a positive meniscus lens L62 having a convex surface facing the object side.

In the variable magnification optical system according to the present Example, upon varying magnification between the wide angle end state and the telephoto end state, all lens groups of the first lens group G1 to the sixth lens group G6 are moved along the optical axis such that a distance between the first lens group G1 and the second lens group G2, a distance between the second lens group G2 and the third lens group G3, a distance between the third lens group G3 and the fourth lens group G4, a distance between the fourth lens group G4 and the fifth lens group G5, and a distance between the fifth lens group G5 and the sixth lens group G6, are varied.

In the variable magnification optical system according to the present Example, focusing from an infinite distance object to a close distance object is carried out by moving, as focusing lens groups, the fourth lens group G4 along the optical axis toward the object side and the fifth lens group G5 along the optical axis toward the object side with a different trajectory from that of the fourth lens group G4.

Table 5 below shows various values of the variable magnification optical system relating to the present Example.

TABLE 5 Fifth Example [Surface Data] m r OP ∞ d nd νd  1 3049.4158 2.000 1.84666 23.80  2 109.9340 7.861 1.81600 46.59  3 −1409.8119 0.200  4 101.3915 6.059 1.81600 46.59  5 503.4410 Variable  *6 239.3378 1.300 1.81600 46.59  7 22.0458 9.224  8 −40.1436 1.300 1.77250 49.62  9 −121.4951 0.200  10 −196.1454 4.421 1.95000 29.37  11 −34.6549 1.015  12 −29.7495 1.300 1.59349 67.00  13 −185.4662 Variable 14 (S) ∞ 0.200  15 47.0680 3.025 1.88300 40.66  16 271.9137 10.130  17 176.7677 2.592 1.59319 67.90  18 −179.0400 0.200  19 86.4232 5.895 1.59319 67.90  20 −27.4209 1.000 1.95000 29.37  21 −41.6214 Variable  22 −33.9616 1.000 1.72825 28.38  23 151.3178 0.200  24 84.0645 3.506 1.71999 50.27  25 −174.4171 Variable  26 140.7071 4.753 1.54814 45.78 *27 −72.5378 Variable *28 −60.3860 1.300 1.74950 35.25  29 326.8097 1.986  30 45.0000 7.770 1.64000 60.19  31 459.8861 BF I ∞ [Aspherical Surface Data] m:6 κ = 1.0000 A4 = 8.90328E−07 A6 = −2.96841E−09 A8 = 5.16084E−12 A10 = −3.05458E−15 m:27 κ = 1.0000 A4 = 2.61448E−06 A6 = 8.65353E−09 A8 = −3.00982E−11 A10 = 4.50822E−14 m:28 κ = 1.0000 A4 = −6.11667E−06 A6 = 9.18242E−09 A8 = −3.76607E−11 A10 = 4.75789E−14 [Various Data] Variable magnification ratio 2.99 W M T f 22.7 49.7 67.9 FNO 2.92 2.92 2.92 2ω 91.48 45.84 32.90 Ymax 19.18 21.60 21.60 TL 157.45 170.49 182.85 BF 14.08 21.92 17.11 W M T W M T f, β 22.701 49.700 67.907 −0.033 −0.033 −0.033 d0  0.000 0.000 0.000 640.708 1420.26 1939.82 d5  2.000 24.596 37.406 2.000 24.596 37.406 d13 35.154 8.040 2.000 35.154 8.040 2.000 d21 4.461 8.442 11.773 4.175 8.108 11.453 d25 20.335 18.256 18.682 18.556 15.932 15.718 d27 2.986 10.795 17.440 5.050 13.453 20.723 [Lens Group Data] Group ST f 1 1 141.872 2 6 −24.424 3 14 30.546 4 22 −75.468 5 26 88.014 6 28 −713.321 [Values for Conditional Expressions]  (1) (−f1N)/|f1| = 0.950  (2) BFw/fw = 0.620  (3) (−fRN)/ft = 1.000  (4) MTF1/MTF2 = 0.098  (5) (−fFN)/|fF| = 0.504  (6) nP/nN = 0.995  (7) |fF1|/|f1| = 0.532  (8) |fF2|/|f1| = 0.620  (9) |fF1|/ft = 1.111 (10) |fF2|/ft = 1.296 (11) |βWF1|/|βWF2| = 2.449 (12) |βRw|/|βRt| = 1.034 (13) ωw = 45.74°

FIG. 14A, FIG. 14B and FIG. 14C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Fifth Example.

FIG. 15A, FIG. 15B and FIG. 15C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Fifth Example.

As is apparent from the above-mentioned graphs showing various aberrations, the variable magnification optical system relating to the present Example can correct superbly various aberrations over the wide angle end state to the telephoto end state and has excellent imaging performance, and further has excellent imaging performance even upon focusing on a close distance object.

Sixth Example

FIG. 16 is a view showing a lens configuration of a variable magnification optical system according to a Sixth Example of the present application.

The variable magnification optical system according to the present Example is composed of, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, an aperture stop S, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power.

The first lens group G1 consists of, in order from the object side, a double convex positive lens L11, and a cemented positive lens constructed by a negative meniscus lens L12 having a convex surface facing the object side cemented with a double convex positive lens L13.

The second lens group G2 consists of, in order from the object side, a double concave negative lens L21, a positive meniscus lens L22 having a convex surface facing the object side and a cemented negative lens constructed by a double concave negative lens L23 cemented with a positive meniscus lens L24 having a convex surface facing the object side.

The third lens group G3 consists of, in order from the object side, a double convex positive lens L31, and a cemented positive lens constructed by a double convex positive lens L32 cemented with a double concave negative lens L33.

The fourth lens group G4 consists of a cemented positive lens constructed by a double convex positive lens L41 cemented with a negative meniscus lens L42 having a concave surface facing the object side.

The fifth lens group G5 consists of a negative meniscus lens L51 having a convex surface facing the object side.

The sixth lens group G6 consists of a positive meniscus lens L61 having a concave surface facing the object side.

The seventh lens group G7 consists of, in order from the object side, a negative meniscus lens L71 having a concave surface facing the object side and a double convex positive lens L72.

In the variable magnification optical system according to the present Example, upon varying magnification between the wide angle end state and the telephoto end state, all lens groups of the first lens group G1 to the seventh lens group G7 are moved along the optical axis such that a distance between the first lens group G1 and the second lens group G2, a distance between the second lens group G2 and the third lens group G3, a distance between the third lens group G3 and the fourth lens group G4, a distance between the fourth lens group G4 and the fifth lens group G5, a distance between the fifth lens group G5 and the sixth lens group G6 and a distance between the sixth lens group G6 and the seventh lens group G7, are varied.

In the variable magnification optical system according to the present Example, focusing from an infinite distance object to a close distance object is carried out by moving, as focusing lens groups, the fourth lens group G4 along the optical axis toward the object side and the sixth lens group G6 along the optical axis toward the object with a different trajectory from that of the fourth lens group G4.

Table 6 below shows various values of the variable magnification optical system relating to the present Example.

TABLE 6 Sixth Example [Surface Data] m r d nd νd OP ∞  1 829.7998 3.542 1.48749 70.32  2 −352.7135 0.200  3 102.3920 1.700 1.67270 32.18  4 65.2892 8.627 1.49700 81.73  5 −4480.3970 Variable  6 −331.7733 1.000 1.77250 49.62  7 47.4606 2.120  8 45.4437 2.785 1.80518 25.45  9 90.1171 3.854 10 −70.4901 1.000 1.67003 47.14 11 34.7167 3.536 1.75520 27.57 12 116.6754 Variable 13 100.8918 3.650 1.80610 40.97 14 −72.8434 0.200 15 48.3355 4.843 1.49700 81.73 16 −53.3052 1.443 1.85026 32.35 17 226.4472 1.323 18(S) ∞ Variable 19 56.3197 4.471 1.51680 63.88 20 −38.8956 1.000 1.80100 34.92 21 −92.0195 Variable 22 513.7755 3.255 1.85026 32.35 23 39.1334 Variable 24 −52.5225 4.182 1.71736 29.57 25 −30.1949 Variable 26 −25.8031 1.873 1.81600 46.59 27 −90.1071 0.200 28 139.7088 3.802 1.79504 28.69 29 −94.4559 BF I ∞ [Various Data] Variable magnification ratio 4.05 W M T f 72.1 100.0 292.0 FNO 4.74 4.81 5.88 2ω 34.32 24.20 8.28 Ymax 21.60 21.60 21.60 TL 193.32 211.66 248.32 BF 38.32 39.78 62.52 W M T W M T f, β 72.100 99.963 292.002 −0.033 −0.033 −0.033 d0 0.000 0.000 0.000 2117.00 2908.95 8607.60 d5 2.000 28.621 75.058 2.000 28.621 75.058 d12 43.058 34.009 2.000 43.058 34.009 2.000 d18 21.601 19.944 21.366 21.096 19.010 19.414 d21 2.000 3.657 2.235 2.505 4.591 4.188 d23 11.246 10.437 10.009 10.564 10.137 9.509 d25 16.489 16.614 16.522 17.171 16.914 17.022 [Lens Group Data] Group ST f 1 1 167.538 2 6 −41.098 3 13 50.455 4 19 95.000 5 22 −49.977 6 24 91.830 7 26 −136.049 [Values for Conditiona Expressions] (1) (−f1N)/|f1| = 1.629 (2) BFw/fw = 0.531 (3) (−fRN)/ft = 0.154 (4) MTF1/MTF2 = 3.903 (5) (−fFN)/|fF| = 0.924 (6) nP/nN = 0.842 (7) |fF1|/|f1| = 0.567 (8) |fF2|/|f1| = 0.548 (9) |fF1|/ft = 0.325 (10) |fF2|/ft = 0.314 (11) |βWF1|/|βwF2| = 1.096 (12) |βRw|/|βRt| = 0.934 (13) ωw = 17.16°

FIG. 17A, FIG. 17B and FIG. 17C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Sixth Example.

FIG. 18A, FIG. 18B and FIG. 18C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Sixth Example.

As is apparent from the above-mentioned graphs showing aberrations, the variable magnification optical system relating to the present Example can correct superbly various aberrations over the wide angle end state to the telephoto end state and has excellent imaging performance, and further has excellent imaging performance even upon focusing on a close distance object.

Seventh Example

FIG. 19 is a view showing a lens configuration of a variable magnification optical system according to a Seventh Example of the present application.

The variable magnification optical system according to the present Example is composed of, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having positive refractive power.

The first lens group G1 consists of, in order from the object side, a cemented positive lens constructed by a negative meniscus lens L11 having a convex surface facing the object side cemented with a double convex positive lens L12, and a positive meniscus lens L13 having a convex surface facing the object side.

The second lens group G2 consists of, in order from the object side, a double concave negative lens L21, a double concave negative lens L22, and a cemented positive lens constructed by a double convex positive lens L23 cemented with a double concave negative lens L24.

The third lens group G3 consists of, in order from the object side, a double convex positive lens L31, and a cemented positive lens constructed by a double convex positive lens L32 cemented with a double concave negative lens L33.

The fourth lens group G4 consists of, in order from the object side, a double convex positive lens L41 and a negative meniscus lens L42 having a concave surface facing the object side.

The fifth lens group G5 consists of a double convex positive lens L51.

The sixth lens group G6 consists of a cemented negative lens constructed by a positive meniscus lens L61 having a concave surface facing the object side cemented with a double concave negative lens L62.

The seventh lens group G7 consists of a positive meniscus lens L71 having a concave surface facing the object side.

In the variable magnification optical system according to the present Example, upon varying magnification between the wide angle end state and the telephoto end state, all lens groups of the first lens group G1 to the seventh lens group G7 are moved along the optical axis such that a distance between the first lens group G1 and the second lens group G2, a distance between the second lens group G2 and the third lens group G3, a distance between the third lens group G3 and the fourth lens group G4, a distance between the fourth lens group G4 and the fifth lens group G5, a distance between the fifth lens group G5 and the sixth lens group G6 and a distance between the sixth lens group G6 and the seventh lens group G7, are varied.

In the variable magnification optical system according to the present Example, focusing from an infinite distance object to a close distance object is carried out by moving, as focusing lens groups, the fourth lens group G4 along the optical axis toward the image side and the fifth lens group G5 along the optical axis toward the object side.

Table 7 below shows various values of the variable magnification optical system relating to the present Example.

TABLE 7 Seventh Example [Surface Data] m r d nd νd OP ∞  1 137.2611 2.000 1.85000 27.03  2 66.9538 6.897 1.59319 67.90  3 −677.5498 0.200  4 107.1491 4.136 1.61800 63.34  5 9353.1970 Variable  *6 −150.8738 2.000 1.90265 35.72  7 25.5606 4.779  8 −260.6181 1.000 1.81600 46.59  9 86.2883 0.200  10 41.4737 5.687 1.84666 23.78  11 −48.7116 1.000 1.81600 46.59  12 54.7043 Variable  13(S) ∞ 0.200  14 44.1680 2.899 1.77250 49.62  15 −280.6415 0.200  16 27.1646 4.022 1.59319 67.90  17 −146.4206 1.000 1.95000 29.37  18 51.2305 Variable  19 50.9241 2.999 1.83481 42.73  20 −182.3279 2.176  21 −80.2256 1.000 1.88300 40.66  22 −715.7217 Variable  23 101.2327 2.235 1.83481 42.73 *24 −257.5032 Variable *25 −283.1336 4.085 1.58144 40.98  26 −18.4049 1.000 1.90366 31.27  27 87.0702 Variable  28 −136.5964 6.525 1.59319 67.90  29 −38.7359 I ∞ [Aspherical Surface Data] m: 6 K = 1.0000 A4 = 1.67289E−07 A6 = −1.03260E−09 A8 = 5.37315E−12 A10 = −4.58982E−15 m: 24 K = 1.0000 A4 = 4.43454E−06 A6 = 2.09008E−08 A8 = −1.49527E−10 A10 = 8.49155E−13 m: 25 K = 1.0000 A4 = −2.21915E−05 A6 = 1.15956E−07 A8 = −1.94063E−09 A10 = 9.93961E−12 [Various Data] Variable magnification ratio 8.50 W M T f 24.7 70.0 210.0 FNO 3.47 5.31 6.52 2ω 85.94 32.52 11.08 Ymax 19.90 21.60 21.60 TL 141.66 173.63 194.45 BF 23.35 32.36 13.26 W M T W M T f, β 24.700 70.005 209.991 −0.033 −0.033 −0.033 d0 0.000 0.000 0.000 706.534 2031.32 6175.90 d5 2.002 22.984 54.077 2.002 22.984 54.077 d12 37.630 16.703 2.000 37.630 16.703 2.000 d18 9.388 7.991 4.000 9.688 8.290 4.039 d22 7.722 6.619 11.160 6.491 5.369 9.139 d24 2.215 7.801 20.136 3.147 8.752 21.938 d27 3.110 22.940 33.576 3.110 22.940 33.576 [Lens Group Data] Group ST f 1 1 113.050 2 6 −19.624 3 13 42.460 4 19 84.928 5 23 87.292 6 25 −33.119 7 28 88.941 [Values for Conditional Expressions] (1) (−f1N)/|f1| = 1.378 (2) BFw/fw = 0.945 (3) (−fRN)/ft = 0.080 (4) MTF1/MTF2 = 0.022 (5) (−fFN)/|fF| = 1.206 (6) nP/nN = 0.974 (7) |fF1|/|f1| = 0.751 (8) |fF2|/|f1| = 0.772 (9) |fF1|/ft = 0.404 (10) |fF2|/ft = 0.416 (11) |βWF1|/|βWF2| = 0.616 (12) |βRw|/|βRt|= 1.858 (13) ωw = 42.97°

FIG. 20A, FIG. 20B and FIG. 20C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Seventh Example.

FIG. 21A, FIG. 21B and FIG. 21C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Seventh Example.

As is apparent from the above-mentioned graphs showing aberrations, the variable magnification optical system relating to the present Example can correct superbly various aberrations over the wide angle end state to the telephoto end state and has excellent imaging performance, and further has excellent imaging performance even upon focusing on a close distance object.

Eighth Example

FIG. 22 is a view showing a lens configuration of a variable magnification optical system according to an Eighth Example of the present application.

The variable magnification optical system according to the present Example is composed of, in order from an object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, an aperture stop S, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power.

The first lens group G1 consists of, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, and a cemented positive lens constructed by a negative meniscus lens L12 having a convex surface facing the object side cemented with a positive meniscus lens L13 having a convex surface facing the object side.

The second lens group G2 consists of, in order from the object side, a cemented positive lens constructed by a double convex positive lens L21 cemented with a negative meniscus lens L22 having a concave surface facing the object side, and a cemented positive lens constructed by a negative meniscus lens L23 having a convex surface facing the object side cemented with a double convex positive lens L24.

The third lens group G3 consists of, in order from the object side, a negative meniscus lens L31 having a concave surface facing the object side and a cemented positive lens constructed by a double concave negative lens L32 cemented with a positive meniscus lens L33 having a convex surface facing the object side.

The fourth lens group G4 consists of a double convex positive lens L41.

The fifth lens group G5 consists of a negative meniscus lens L51 having a concave surface facing the object side.

The sixth lens group G6 consists of a double convex positive lens L61.

The seventh lens group G7 consists of a negative meniscus lens L71 having a concave surface facing the object side.

In the variable magnification optical system according to the present Example, upon varying magnification between the wide angle end state and the telephoto end state, all lens groups of the first lens group G1 to the seventh lens group G7 are moved along the optical axis such that a distance between the first lens group G1 and the second lens group G2, a distance between the second lens group G2 and the third lens group G3, a distance between the third lens group G3 and the fourth lens group G4, a distance between the fourth lens group G4 and the fifth lens group G5, a distance between the fifth lens group G5 and the sixth lens group G6 and a distance between the sixth lens group G6 and the seventh lens group G7, are varied.

In the variable magnification optical system according to the present Example, focusing from an infinite distance object to a close distance object is carried out by moving, as focusing lens groups, the fourth lens group G4 along the optical axis toward the object side, and the fifth lens group G5 and the sixth lens group G6 along the optical axis toward the object side with different trajectories, respectively, from that of the fourth lens group G4.

Table 8 below shows various values of the variable magnification optical system relating to the present Example.

TABLE 8 Eighth Example [Surface Data] m r d nd νd OP ∞  1 250.0000 2.900 1.74389 49.53  *2 28.0269 12.424  3 154.1167 2.100 1.59349 67.00  4 32.5416 6.969 2.00069 25.46  5 61.8764 Variable  6 175.0869 5.997 1.81600 46.59  7 −52.8034 1.500 1.85000 27.03  8 −204.9882 1.000  9 45.2860 1.500 1.80518 25.45  10 26.6188 11.527 1.60300 65.44  11 −76.6492 Variable  12(S) ∞ 2.465  13 −64.5009 1.300 1.90265 35.72  14 −217.6883 0.200  15 −214.1041 1.300 1.67270 32.18  16 26.6878 6.400 1.80809 22.74  17 502.6822 Variable  18 65.6282 5.000 1.48749 70.32  19 −65.3105 Variable  20 −52.0851 1.300 1.84666 23.80  21 −201.9547 Variable  22 185.0000 5.300 1.58913 61.15 *23 −50.5905 Variable *24 −27.3977 1.500 1.58913 61.15  25 −49.4756 BF I ∞ [Aspherical Data] m: 2 K = 0.0000 A4 = 3.95960E−06 A6 = 3.76748E−09 A8 = −5.23494E−12 A10 = 1.04782E−14 A12 = −4.82160E−18 m: 23 K = 1.0000 A4 = 6.76320E−06 A6 = −8.33082E−09 A8 = 3.88079E−11 A10 = −7.09278E−14 m: 24 K = 1.0000 A4 = 5.00393E−06 A6 = −8.92918E−09 A8 = 2.86537E−11 A10 = −5.32582E−14 [Various Data] Variable magnification ratio 2.99 W M T f 22.7 50.0 67.9 FNO 3.03 3.00 3.03 2ω 91.04 45.96 33.62 Ymax 19.30 21.60 21.60 TL 188.49 155.49 167.35 BF 16.20 23.37 32.67 W M T W M T f, β 22.700 49.999 67.899 −0.033 −0.033 −0.033 d0 0.000 0.000 0.000 644.489 1474.05 2002.27 d5 64.883 10.266 5.946 64.883 10.266 5.946 d11 2.200 12.775 27.038 2.200 12.775 27.038 d17 20.035 8.462 6.571 19.026 7.439 4.593 d19 2.030 3.706 4.816 1.360 3.164 4.349 d21 4.601 9.046 14.467 4.908 8.936 15.092 d23 7.862 17.178 5.159 9.234 18.853 6.979 [Lens Group Data] Group ST f 1 1 −42.744 2 6 40.599 3 12 −105.371 4 18 68.000 5 20 −83.229 6 22 68.000 7 24 −106.909 [Values for Conditional Expressions] (1) (−f1N)/|f1| = 0.998 (2) BFw/fw = 0.713 (3) (−fRN)/ft = 1.575 (4) MTF1/MTF2 = 0.809 (5) (−fFN)/|fF| = 1.224 (6) nP/nN = 0.806 (7) |fF1|/|f1| = 1.591 (8) |fF2|/|f1| = 1.591 (9) |fF1|/ft = 1.001 (10) |fF2|/ft = 1.001 (11) |βWF1|/|βWF2| = 0.350 (12) |βRw|/|βRt| = 1.387 (13) ωw = 45.52°

FIG. 23A, FIG. 23B and FIG. 23C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Eighth Example.

FIG. 24A, FIG. 24B and FIG. 24C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Eighth Example.

As is apparent from the above-mentioned graphs showing aberrations, the variable magnification optical system relating to the present Example can correct superbly various aberrations over the wide angle end state to the telephoto end state and has excellent imaging performance, and further has excellent imaging performance even upon focusing on a close distance object.

Ninth Example

FIG. 25 is a view showing a lens configuration of a variable magnification optical system according to a Ninth Example.

The variable magnification optical system according to the present Example is composed of, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power.

The first lens group G1 consists of, in order from the object side, a cemented negative lens constructed by a negative meniscus lens L11 having a convex surface facing the object side cemented with a double convex positive lens L12, and a positive meniscus lens L13 having a convex surface facing the object side.

The second lens group G2 consists of, in order from the object side, a double concave negative lens L21, and a cemented negative lens constructed by a negative meniscus lens L22 having a concave surface facing the object side cemented with a positive meniscus lens L23 having a concave surface facing the object side cemented with a negative meniscus lens L24 having a concave surface facing the object side.

The third lens group G3 consists of, in order from the object side, a positive meniscus lens L31 having a convex surface facing the object side, a cemented positive lens constructed by a negative meniscus lens L32 having a convex surface facing the object side cemented with a positive meniscus lens L33 having a convex surface facing the object side, and a double convex positive lens L34.

The fourth lens group G4 consists of, in order from the object side, a positive meniscus lens L41 having a concave surface facing the object side and a double concave negative lens L42.

The fifth lens group G5 consists of a cemented positive lens constructed by a double convex positive lens L51 cemented with a negative meniscus lens L52 having a concave surface facing the object side.

The sixth lens group G6 consists of a positive meniscus lens L61 having a concave surface facing the object side.

The seventh lens group G7 consists of a double concave negative lens L71.

In the variable magnification optical system according to the present Example, upon varying magnification between the wide angle end state and the telephoto end state, all lens groups of the first lens group G1 to the seventh lens group G7 are moved along the optical axis such that a distance between the first lens group G1 and the second lens group G2, a distance between the second lens group G2 and the third lens group G3, a distance between the third lens group G3 and the fourth lens group G4, a distance between the fourth lens group G4 and the fifth lens group G5, a distance between the fifth lens group G5 and the sixth lens group G6 and a distance between the sixth lens group G6 and the seventh lens group G7, are varied.

In the variable magnification optical system according to the present Example, focusing from an infinite distance object to a close distance object is carried out by moving, as focusing lens groups, the fifth lens group G5 along the optical axis toward the object side, and the sixth lens group G6 along the optical axis toward the object side with a different trajectory from that of the fifth lens group G5.

Table 9 below shows various values of the variable magnification optical system relating to the present Example.

TABLE 9 Ninth Example [Surface Data] m r d nd νd OP ∞  1 3442.9453 2.000 2.00100 29.12  2 67.9723 9.758 1.59319 67.90  3 −152.3923 0.200  4 58.4962 5.618 1.81600 46.59  5 401.1678 Variable  *6 −290.9507 1.400 1.88300 40.66  7 23.9500 5.968  8 −85.0139 1.200 1.83481 42.73  9 −120.7468 5.617 1.84666 23.80  10 −22.1853 1.200 1.81600 46.59  11 −285.7763 Variable  12(S) ∞ 0.200  13 43.7782 3.108 1.69680 55.52  14 471.1855 0.200  15 32.7556 1.000 1.83481 42.73  16 21.7787 4.328 1.59319 67.90  17 90.7958 0.200  18 34.8267 4.022 1.58144 40.98  19 −155.1147 Variable *20 −30.2170 1.817 1.90200 25.26  21 −25.8045 0.200  22 −168.2619 1.000 1.90366 31.27  23 32.2596 Variable  24 38.3747 4.859 1.49700 81.73  25 −32.4370 1.000 2.00069 25.46  26 −70.7616 Variable  27 −63.4136 3.063 1.56732 42.58 *28 −25.4716 Variable *29 −40.3736 1.500 1.81600 46.59  30 223.1585 BF I ∞ [Aspherical Surface Data] m: 6 K = 1.0000 A4 = 1.12990E−06 A6 = −1.48448E−09 A8 = 2.59485E−12 A10 = −2.03608E−15 m: 20 K = 1.0000 A4 = −1.25538E−05 A6 = 2.12431E−08 A8 = −1.35330E−10 A10 = 4.53472E−13 m: 28 K = 1.0000 A4 = 2.57266E−05 A6 = 5.03605E−08 A8 = −2.10329E−10 A10 = 3.98690E−13 m: 29 x = 1.0000 A4 = 1.23110E−05 A6 = 2.00664E−08 A8 = −1.99371E−10 A10 = 2.96093E−13 [Various Data] Variable magnification ratio 8.97 W M T f 24.8 70.0 222.0 FNO 3.69 5.39 6.42 2ω 85.32 33.28 10.80 Ymax 20.30 21.60 21.60 TL 152.38 168.67 204.50 BF 13.25 40.90 75.50 W M T W M T f, β 24.750 70.000 222.000 −0.033 −0.033 −0.033 d0 0.000 0.000 0.000 708.545 2047.97 6602.17 d5 2.000 19.489 42.969 2.000 19.489 42.969 d11 40.184 17.902 2.000 40.184 17.902 2.000 d19 2.003 3.971 9.577 2.003 3.971 9.577 d23 10.844 6.751 7.946 10.369 6.000 6.221 d26 15.034 12.261 4.050 14.947 12.499 5.206 d28 9.603 7.938 3.000 10.165 8.452 3.568 [Lens Group Data] Group ST f 1 1 93.169 2 6 −21.680 3 12 24.825 4 20 −35.481 5 24 85.936 6 27 72.909 7 29 −41.791 [Values for Conditional Expressions] (1) (−f1N)/|f1| = 0.744 (2) BFw/fw = 0.536 (3) (−fRN)/ft = 0.188 (4) MTF1/MTF2 = 3.034 (5) (−fFN)/|fF| = 0.832 (6) nP/nN = 0.786 (7) |fF1|/|f1| = 0.922 (8) |fF2|/|f1| = 0.783 (9) |fF1|/ft = 0.387 (10) |fF2|/ft = 0.328 (11) |βWF1|/|βWF2| = 0.607 (12) |βRwl/βRt| = 0.815 (13) ωw = 42.66°

FIG. 26A, FIG. 26B and FIG. 26C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Ninth Example.

FIG. 27A, FIG. 27B and FIG. 27C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Ninth Example.

As is apparent from the above-mentioned graphs showing aberrations, the variable magnification optical system relating to the present Example can correct superbly various aberrations over the wide angle end state to the telephoto end state and has excellent imaging performance, and further has excellent imaging performance even upon focusing on a close distance object.

Tenth Example

FIG. 28 is a view showing a lens configuration of a variable magnification optical system according to a Tenth Example.

The variable magnification optical system according to the present Example is composed of, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, an aperture stop S, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power.

The first lens group G1 consists of, in order from the object side, a double convex positive lens L11, and a cemented positive lens constructed by a negative meniscus lens L12 having a convex surface facing the object side cemented with a double convex positive lens L13.

The second lens group G2 consists of, in order from the object side, a negative meniscus lens L21 having a convex surface facing the object side, a positive meniscus lens L22 having a convex surface facing the object side, and a cemented negative lens constructed by a double concave negative lens L23 cemented with a positive meniscus lens L24 having a convex surface facing the object side.

The third lens group G3 consists of, in order from the object side, a double convex positive lens L31, and a cemented positive lens constructed by a double convex positive lens L32 cemented with a double concave negative lens L33.

The fourth lens group G4 consists of a cemented positive lens constructed by a negative meniscus lens L41 having a convex surface facing the object side cemented with a double convex positive lens L42.

The fifth lens group G5 consists of, in order from the object side, a double convex positive lens L51 and a double concave negative lens L52.

The sixth lens group G6 consists of, in order from the object side, a negative meniscus lens L61 having a concave surface facing the object side and a double convex positive lens L62.

In the variable magnification optical system according to the present Example, upon varying magnification between the wide angle end state and the telephoto end state, all lens groups of the first lens group G1 to the sixth lens group G6 are moved along the optical axis such that a distance between the first lens group G1 and the second lens group G2, a distance between the second lens group G2 and the third lens group G3, a distance between the third lens group G3 and the fourth lens group G4, a distance between the fourth lens group G4 and the fifth lens group G5, and a distance between the fifth lens group G5 and the sixth lens group G6, are varied.

In the variable magnification optical system according to the present Example, focusing from an infinite distance object to a close distance object is carried out by moving, as focusing lens groups, the fourth lens group G4 along the optical axis toward the object side and the fifth lens group G5 along the optical axis toward the image side.

Table 10 below shows various values of the variable magnification optical system relating to the present Example.

TABLE 10 Tenth Example [Surface Data] m r d nd νd OP ∞  1 339.1302 3.342 1.48749 70.32  2 −1748.8042 0.200  3 113.3340 1.700 1.62004 36.40  4 62.3111 8.286 1.49700 81.73  5 −790.8224 Variable  6 452.0591 1.300 1.80400 46.60  7 41.1492 4.042  8 41.3304 3.091 1.68893 31.16  9 98.8092 4.158 10 −68.4923 1.000 1.70000 48.10 11 36.0772 3.318 1.80518 25.45 12 117.8747 Variable 13 180.8711 3.540 1.80400 46.60 14 −64.2101 0.200 15 40.7438 5.229 1.49700 81.73 16 −52.5435 1.200 1.85026 32.35 17 200.0407 1.376 18(S) ∞ Variable 19 68.3281 1.200 1.71736 29.57 20 20.1023 6.000 1.56732 42.58 21 −61.5874 Variable 22 188.7697 2.905 1.72825 28.38 23 −56.4394 0.719 24 −72.6983 1.000 1.80400 46.60 25 30.9300 Variable 26 −22.2025 1.300 1.69680 55.52 27 −38.2594 0.200 28 95.0769 3.373 1.80610 40.97 29 −205.8129 BF I ∞ [Various Data] Variable magnification ratio 4.05 W M T f 72.1 100.0 292.0 FNO 4.68 4.86 5.88 2ω 33.86 24.02 8.26 Ymax 21.60 21.60 21.60 TL 193.32 209.38 244.81 BF 38.32 41.53 60.32 W M T W M T f, β 72.100 100.000 292.000 −0.033 −0.033 −0.033 d0 0.000 0.000 0.000 2108.51 2898.12 8529.76 d5 2.000 26.301 76.285 2.000 26.301 76.285 d12 45.791 35.345 2.000 45.791 35.345 2.000 d18 29.471 29.387 29.007 28.880 29.181 28.801 d21 2.000 3.362 2.000 2.786 4.328 3.858 d25 16.057 14.780 16.521 15.862 14.019 14.868 [Lens Group Data] Group ST f 1 1 171.900 2 6 −43.196 3 13 51.979 4 19 82.476 5 22 −51.000 6 26 48383.794 [Values for Conditional Expressions] (1) (−f1N)/|f1| = 1.315 (2) BFw/fw = 0.531 (3) (−fRN)/ft = 0.269 (4) MTF1/MTF2 = 0.125 (5) (−fFN)/|fF| = 0.527 (6) nP/nN = 0.913 (7) |fF1|/|f1| = 0.480 (8) |fF2|/|f1| = 0.297 (9) |fF1|/ft = 0.282 (10) |fF2|/ft = 0.175 (11) |βWF1|/|βWF2| = 0.288 (12) |βRw|/|βRt| = 0.911 (13) ωw = 16.93°

FIG. 29A, FIG. 29B and FIG. 29C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Tenth Example.

FIG. 30A, FIG. 30B and FIG. 30C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Tenth Example.

As is apparent from the above-mentioned graphs showing aberrations, the variable magnification optical system relating to the present Example can correct superbly various aberrations over the wide angle end state to the telephoto end state and has excellent imaging performance, and further has excellent imaging performance even upon focusing on a close distance object.

Eleventh Example

FIG. 31 is a view showing a lens configuration of a variable magnification optical system according to an Eleventh Example.

The variable magnification optical system according to the present Example is composed of, in order from an object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, an aperture stop S, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power.

The first lens group G1 consists of, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, and a cemented positive lens constructed by a double concave negative lens L12 cemented with a positive meniscus lens L13 having a convex surface facing the object side.

The second lens group G2 consists of a cemented positive lens constructed by a double convex positive lens L21 cemented with a negative meniscus lens L22 having a concave surface facing the object side.

The third lens group G3 consists of a cemented positive lens constructed by a negative meniscus lens L31 having a convex surface facing the object side cemented with a double convex positive lens L32.

The fourth lens group G4 consists of a cemented negative lens constructed by a double concave negative lens L41 cemented with a positive meniscus lens L42 having a convex surface facing the object side.

The fifth lens group G5 consists of a double convex positive lens L51.

The sixth lens group G6 consists of a double convex positive lens L61.

The seventh lens group G7 consists of a negative meniscus lens L71 having a concave surface facing the object side.

In the variable magnification optical system according to the present Example, upon varying magnification between the wide angle end state and the telephoto end state, all lens groups of the first lens group G1 to the seventh lens group G7 are moved along the optical axis such that a distance between the first lens group G1 and the second lens group G2, a distance between the second lens group G2 and the third lens group G3, a distance between the third lens group G3 and the fourth lens group G4, a distance between the fourth lens group G4 and the fifth lens group G5, a distance between the fifth lens group G5 and the sixth lens group G6 and a distance between the sixth lens group G6 and the seventh lens group G7, are varied.

In the variable magnification optical system according to the present Example, focusing from an infinite distance object to a close distance object is carried out by moving, as focusing lens groups, the fifth lens group G5 along the optical axis toward the object side, and the sixth lens group G6 along the optical axis toward the object side with a different trajectory from that of the fifth lens group G5.

Table 11 below shows various values of the variable magnification optical system relating to the present Example.

TABLE 11 Eleventh Example [Surface Data] m r d nd νd OP ∞  1 260.0000 2.900 1.74389 49.53  *2 30.1702 13.784  3 −1991.6463 2.100 1.59349 67.00  4 33.7055 8.364 2.00100 29.13  5 89.6077 Variable  6 108.4958 8.489 1.80100 34.92  7 −30.7757 1.500 1.80518 25.45  8 −204.3062 Variable  9 45.1018 1.500 1.85000 27.03  10 24.0000 9.603 1.59319 67.90  11 −88.4112 Variable  12(S) ∞ 1.733  13 −63.2999 1.300 1.65100 56.24  14 36.0420 2.727 1.90265 35.72  15 90.4648 Variable  16 139.2934 5.000 1.48749 70.32  17 −72.7540 Variable  18 554.8019 4.200 1.58913 61.15 *19 −54.8898 Variable *20 −29.0077 1.500 1.84666 23.80  21 −45.1973 BF I ∞ [Aspherical Data] m: 2 K = 0.0000 A4 = 3.70839E−06 A6 = 7.95920E−10 A8 = 7.22303E−12 A10 = −1.14971E−14 A12 = 9.51080E−18 m: 19 K = 1.0000 A4 = 5.13891E−06 A6 = −3.95654E−09 A8 = 1.36188E−11 A10 = −1.64821E−14 m: 20 K = 1.0000 A4 = 4.54393E−06 A6 = −1.30549E−09 A8 = 6.99274E−13 A10 = 4.71450E−15 [Various Data] Variable magnification ratio 2.99 W M T f 22.7 50.0 67.9 FNO 4.21 5.58 5.88 2ω 92.68 46.22 33.64 Ymax 19.70 21.60 21.60 TL 188.49 156.49 166.42 BF 14.19 21.35 26.73 W M T W M T f, β 22.700 50.000 67.900 −0.033 −0.033 −0.033 d0 0.000 0.000 0.000 642.626 1479.20 2020.08 d5 62.024 9.333 2.263 62.024 9.333 2.263 d8 1.536 1.576 1.000 1.536 1.576 1.000 d11 2.200 6.706 19.808 2.200 6.706 19.808 d15 25.740 8.889 12.359 25.733 7.830 10.488 d17 3.523 29.546 31.736 2.523 29.489 32.585 d19 14.577 14.391 7.819 15.584 15.506 8.840 [Lens Group Data] Group ST f 1 1 −47.325 2 6 90.647 3 9 68.586 4 12 −74.902 5 16 98.800 6 18 85.000 7 20 −99.892 [Values for Conditional Expressions] (1) (−f1N)/|f1| = 0.975 (2) BFw/fw = 0.625 (3) (−fRN)/ft = 1.471 (4) MTF1/MTF2 = 1.831 (7) |fF1|/|f1| = 2.088 (8) |fF2|/|f1| = 1.796 (9) |fF1|/ft = 1.455 (10) |fF2|/ft = 1.252 (11) |βWF1|/|βWF2| = 0.764 (12) |βRw|/|βRt| = 2.455 (13) ωw = 46.34°

FIG. 32A, FIG. 32B and FIG. 32C are graphs showing various aberrations upon focusing on an infinite distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Eleventh Example.

FIG. 33A, FIG. 33B and FIG. 33C are graphs showing various aberrations upon focusing on a close distance object, respectively, in the wide angle end state, in the intermediate focal length state and in the telephoto end state, of the variable magnification optical system according to the Eleventh Example.

As is apparent from the above-mentioned graphs showing aberrations, the variable magnification optical system relating to the present Example can correct superbly various aberrations over the wide angle end state to the telephoto end state and has excellent imaging performance, and further has excellent imaging performance even upon focusing on a close distance object.

According to each of the above described Examples, it is possible to realize a variable magnification optical system which can suppress superbly variations in aberrations upon varying magnification from a wide angle end state to a telephoto end state and variations in aberrations upon carrying out focusing from an infinite distance object to a close distance object. Further, according to each of the above described Examples, since the focusing lens group(s) is(are) made light in weight and small in size, driving mechanism for the focusing lens group(s) is also downsized, so it is possible to realize high speed as well as noiseless focusing operation without making lens barrel large.

Meanwhile, it is noted that each of the above described Examples is a concrete example of the invention of the present application, and the invention of the present application is not limited to them. The contents described below can be adopted appropriately without deteriorating optical performance of the variable magnification optical systems according to the present embodiment.

Although variable magnification optical systems having a six group configuration and a seven group configuration, were illustrated above as numerical examples of the variable magnification optical systems according to the present embodiment, the present embodiment is not limited to them and variable magnification optical systems having other configurations, such as eight group configuration or the like, can be configured. Concretely, a configuration that a lens or a lens group is added to the most object side or the most image side of the variable magnification optical system according to each of the above described Examples is possible. Alternatively, a lens or a lens group may be added between the neighboring lens groups.

Further, in each of the above described Examples, two or three lens groups are adopted as focusing lens groups, but a part in lens group, or four or more lens groups may be adopted for focusing lens group(s). Each of the focusing lens groups may be composed of one or two lens components, and a configuration composed of one lens component is more preferable. Auto focusing can be applied for such focusing group(s), and drive by motor for auto focusing, such as, ultrasonic motor, stepping motor, and VCM motor may be suitably adopted.

Further, in the variable magnification optical systems according to each of the above described Examples, any lens group in the entirety thereof or a portion thereof can be moved in a direction including a component perpendicular to the optical axis as a vibration reduction lens group, or rotationally moved (swayed) in an in-plane direction including the optical axis, whereby a configuration of a vibration reduction can be taken.

Further, in the variable magnification optical systems according to each of the above described Examples, a lens surface of a lens may be a spherical surface, a plane surface, or an aspherical surface. When a lens surface is a spherical surface or a plane surface, lens processing, assembling and adjustment become easy, and it is possible to prevent deterioration in optical performance caused by lens processing, assembling and adjustment errors, so that it is preferable. Moreover, even if an image plane is shifted, deterioration in depiction performance is little, so that it is preferable. When a lens surface is an aspherical surface, the aspherical surface may be fabricated by a grinding process, a glass molding process that a glass material is formed into an aspherical shape by a mold, or a compound type process that a resin material is formed into an aspherical shape on a glass lens surface. A lens surface may be a diffractive optical surface, and a lens may be a graded-index type lens (GRIN lens) or a plastic lens.

Further, in the variable magnification optical system according to each of the above described Examples, it is preferable that the aperture stop S is disposed between the second lens group G2 and the third lens group G3, or between the third lens group G3 and the fourth lens group G4. But, the function may be substituted by a lens frame without disposing a member as an aperture stop.

Moreover, the lens surface(s) of the lenses configuring the variable magnification optical system according to each of the above described Examples, may be coated with anti-reflection coating(s) having a high transmittance in a wide wavelength region. With this contrivance, it is feasible to reduce a flare as well as ghost and attain excellent optical performance with high contrast.

Next, a camera equipped with the variable magnification optical system according to the present embodiment, will be explained with referring to FIG. 34. FIG. 34 is a view showing a configuration of the camera equipped with the variable magnification optical system according to the present embodiment. The camera 1, as shown in FIG. 34, is a so-called mirror-less camera of a lens interchangeable type equipped with the variable magnification optical system according to the first Example as an imaging lens 2.

In the present camera 1, a light emitted from an unillustrated object (an object to be photo-taken) is converged by the imaging lens 2, through an unillustrated OLPF (Optical low pass filter), and forms an image of the object on an imaging plane of an imaging portion 3. The light from the object is photo-electrically converted through a photo-electric conversion element provided on the imaging portion 3 to forma picture image of the object. This picture image is displayed on an EVF (electric view finder) 4 provided on the camera 1. Accordingly, a photographer can observe the object to be photo-taken through the EVF.

Further, upon unillustrated release button being depressed by the photographer, the picture image of the object formed by the imaging portion 3 is stored in an unillustrated memory. Thus, the photographer can take a photo of the object by the camera 1.

It is noted here that the variable magnification optical system relating to the First Example mounted on the camera 1 as the imaging lens 2, has superb optical performance as described above and the focusing lens group(s) is (are) made light in weight and small in size. In other words, the present camera 1 can realize high optical performance that variations in aberrations upon varying magnification from the wide angle end state to the telephoto end state as well as variations in aberrations upon carrying out focusing from an infinite distance object to a close distance object, can be suppressed, and realize high speed focusing, by making the focusing lens group(s) small in size and light.

Incidentally, even in a case where a camera in which the variable magnification optical system according to any of the before-mentioned Second to Eleventh Examples is installed as the imaging lens 2, is configured, the camera also can attain the same effects as those of the above-mentioned camera 1. Further, even when the variable magnification optical system according to any of the Examples is installed in a camera of a single lens reflex type equipped with a quick return mirror in which the object image is observed through a finder optical system, the camera also can have the same effects as those of the above-mentioned camera 1.

Next, an outline of a method for manufacturing the variable magnification optical system according to the present embodiment, is described with referring to FIG. 35.

FIG. 35 is a flowchart schematically showing a method for manufacturing the variable magnification optical system according to the present embodiment.

The method for manufacturing the variable magnification optical system according to the present embodiment shown in FIG. 35, is a method for manufacturing a variable magnification optical system which comprises, in order from an object side, a first lens group and a plurality of lens groups; the method comprising the following steps S1 to S3.

Step S1: preparing a first lens group and a plurality of lens groups, and constructing such that, upon varying magnification, a distance between the first lens group and the plurality of lens groups is varied, and distances between respective lens groups of the plurality of lens groups are varied;

Step S2: constructing such that the plurality of lens groups comprises an object side focusing lens group which is moved upon carrying out focusing and at least one image side focusing lens group disposed in a more image side than the object side focusing lens group and moved with a trajectory differing from that of the object side focusing lens group, upon carrying out the focusing; and

Step S3: constructing such that said variable magnification optical system satisfies the following conditional expressions (1) and (2):

0.60<(−f1N)/|f1|<1.80  (1)

0.2<BFw/fw<2.0  (2)

where f1N denotes a focal length of a lens which has a strongest negative refractive power in lenses in said first lens group, f1 denotes a focal length of said first lens groups, BFw denotes a back focus of said variable magnification optical system in the wide angle end state, and fw denotes a focal length of said variable magnification optical system in the wide angle end state.

According to the above-stated method for manufacturing the variable magnification optical system according to the present embodiment, it is possible to manufacture a variable magnification optical system which can realize high optical performance that variations in aberrations upon varying magnification from the wide angle end state to the telephoto end state as well as variations in aberrations upon carrying out focusing from an infinite distance object to a close distance object, can be suppressed superbly, and of which focusing lens group(s) is and reduced in weight by which high speed focusing operation can be realized.

EXPLANATION OF REFERENCE SYMBOLS

-   -   G1 first lens group     -   G2 second lens group     -   G3 third lens group     -   G4 fourth lens group     -   G5 fifth lens group     -   G6 sixth lens group     -   G7 seventh lens group     -   S aperture stop     -   I image plane     -   1 camera     -   2 imaging lens 

1. A variable magnification optical system comprising, in order from an object side, a first lens group and a plurality of lens groups; upon varying a magnification, a distance between said first lens group and said plurality of lens groups being varied, and distances between respective lens groups in said plurality of lens groups being varied; said plurality of lens groups comprising an object side focusing lens group which is moved upon carrying out focusing and at least one image side focusing lens group disposed in a more image side than the object side focusing lens group and moved with a trajectory differing from that of the object side focusing lens group, upon carrying out the focusing; and the following conditional expressions being satisfied: 0.60<(−f1N)/|f1|<1.80 0.2<BFw/fw<2.0 where f1N denotes a focal length of a lens which has a strongest negative refractive power in lenses in said first lens group, f1 denotes a focal length of said first lens groups, BFw denotes a back focus of said variable magnification optical system in the wide angle end state, and fw denotes a focal length of said variable magnification optical system in the wide angle end state.
 2. A variable magnification optical system according to claim 1, wherein said object side focusing lens group has positive refractive power.
 3. A variable magnification optical system according to claim 1, wherein the focusing lens group disposed in a most image side in said image side focusing lens group, has positive refractive power.
 4. A variable magnification optical system according to claim 1, wherein said object side focusing lens group is composed of one or two lens components.
 5. A variable magnification optical system according to claim 1, wherein said image side focusing lens group is composed of one or two lens components.
 6. A variable magnification optical system according to claim 1, wherein said first lens group is fixed upon carrying out focusing.
 7. A variable magnification optical system according to claim 1m comprising at least one lens component in a more image side than the focusing lens group disposed in the most image side in the image side focusing lens group, and the following conditional expression being satisfied: 0.05<(−fRN)/ft<4.50 where fRN denotes a focal length of the lens having the strongest refractive power in lenses composing said lens components, and ft denotes a focal length of the variable magnification optical system in the telephoto end state.
 8. A variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied: MTF1/MTF2<5.0 where MTF1 denotes an absolute value of a movement amount of said object side focusing lens group upon carrying out the focusing from the infinite distance object to the close distance object in the telephoto end state, and MTF2 denotes an absolute value of a movement amount of the focusing lens group disposed in the most object side in said image side focusing lens group, upon carrying out the focusing from the infinite distance object to the close distance object in the telephoto end state.
 9. A variable magnification optical system according to claim 1, wherein at least one focusing lens group in said object side focusing lens group and said image side focusing lens group comprises at least one lens having negative refractive power; and the following conditional expression is satisfied: 0.45<(−fFN)/|fF|<1.70 where fFN denotes a focal length of the lens having the strongest negative refractive power in lenses in said object side focusing lens group and said image side focusing lens group, and fF denotes a focal length of the focusing lens group having the strongest refractive power in said object side focusing lens group and said image side focusing lens group.
 10. A variable magnification optical system according to claim 1, wherein at least one focusing lens group in said object side focusing lens group and said image side focusing lens group, comprises at least one lens having negative refractive power, and that the following conditional expression is satisfied: 0.65<nP/nN<1.10 where nP denotes refractive index of the lens having the strongest positive refractive power in lenses in said object side focusing lens group and said image side focusing lens group, and nN denotes refractive index of the lens having the strongest negative refractive power in lenses in said object side focusing lens group and said image side focusing lens group.
 11. A variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied: 0.40<|fF1|/|f1|<2.60 where fF1 denotes a focal length of said object side focusing lens group, and f1 denotes a focal length of said first lens group.
 12. A variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied: 0.20<|fF2|/|f1|<3.80 where fF2 denotes a focal length of the focusing lens group disposed in the most image side in said image side focusing lens group, and f1 denotes a focal length of said first lens group.
 13. A variable magnification optical system according to claim 1, wherein said object side focusing lens group consists of, in order from the object side, a lens having positive refractive power and a lens having negative refractive power.
 14. A variable magnification optical system according to claim 1, comprising an aperture stop, and said object side focusing lens group being disposed in more image side than said aperture stop.
 15. A variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied: 0.10<|fF1|/ft<3.00 where fF1 denotes a focal length of said object side focusing lens group, and ft denotes a focal length of said variable magnification optical system in the telephoto end state.
 16. A variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied: 0.10<|fF2|/ft<3.00 where fF2 denotes a focal length of the focusing lens group disposed in the most image side in said image side focusing lens group, and ft denotes a focal length of said variable magnification optical system in the telephoto end state.
 17. A variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied: |βWF1|/|βWF2|<4.00 where βWF1 denotes a transverse magnification of said object side focusing lens group in the wide angle end state upon focusing on an infinite distance object, and βWF2 denotes a transverse magnification of the focusing lens group disposed in the most object side in said image side focusing lens group in the wide angle end state upon focusing on the infinite distance object.
 18. A variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied: |βRw|/|βRt|<4.00 where βRw denotes a composite transverse magnification from said object side focusing lens group to the image plane in the wide angle end state upon focusing on an infinite distance object, and βRt denotes a composite transverse magnification from the object side focusing lens group to the image plane in the telephoto end state upon focusing on the infinite distance object.
 19. A variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied: 15.0°<ωw<85.0° where ωw denotes a half angle of view of said focusing lens group in the wide angle end state.
 20. An optical apparatus comprising a variable magnification optical system according to claim
 1. 21. A method for manufacturing a variable magnification optical system which comprises, in order from an object side, a first lens group and a plurality of lens groups; comprising the steps of: constructing such that, upon varying a magnification, a distance between said first lens group and said plurality of lens groups is varied, and distances between respective lens groups in said plurality of lens groups are varied; constructing such that said plurality of lens groups comprise an object side focusing lens group which is moved upon carrying out focusing and at least one image side focusing lens group disposed in more image side than said object side focusing lens group and moved with a trajectory differing from that of said object side focusing lens group, upon carrying out the focusing; and constructing such that the following conditional expressions are satisfied: 0.60<(−f1N)/|f1|<1.80 0.2<BFw/fw<2.0 where f1N denotes a focal length of a lens which has a strongest negative refractive power in lenses in said first lens group, f1 denotes a focal length of said first lens groups, BFw denotes a back focus of said variable magnification optical system in the wide angle end state, and fw denotes a focal length of said variable magnification optical system in the wide angle end state. 